Internal Medicine

3151 soru

Soru 1381Soru →

A 62-year-old woman with a body mass index of 34 kg/m² presents to the clinic with chronic, progressive bilateral knee pain. She notes the pain worsens with weight-bearing activities, such as walking up stairs, and is relieved by rest. She experiences morning stiffness in her knees lasting approximately 15 minutes. Physical examination reveals bony enlargement, crepitus, and a limited range of motion in both knees, without significant warmth or large effusions. Radiographs demonstrate asymmetric joint space narrowing, subchondral sclerosis, and prominent osteophyte formation. Arrange the following management steps for this patient's condition in the most appropriate sequential order, progressing from initial conservative measures to definitive advanced interventions.

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Cevap

The correct sequence of management is: 1) Weight loss, physical therapy, and topical NSAIDs; 2) Oral NSAIDs or duloxetine; 3) Intra-articular glucocorticoid injections; 4) Orthopedic surgery referral.
The management of knee osteoarthritis follows a stepwise escalation to balance efficacy and safety. Initial therapy involves nonpharmacologic measures (weight loss, exercise) and topical NSAIDs, which minimize systemic exposure. If inadequate, therapy is escalated to oral NSAIDs or duloxetine. For continued severe symptoms or acute flares, intra-articular glucocorticoid injections provide targeted relief. Finally, when all medical therapies have been exhausted and the patient's quality of life is severely impacted, referral for total knee arthroplasty is indicated.

Adım Adım Çözüm

1
Identify the patient's diagnosis based on the clinical and radiographic presentation.
The patient has symptomatic knee osteoarthritis, supported by her age, obesity, mechanical joint pain, brief morning stiffness, and classic radiographic findings (joint space narrowing, osteophytes, subchondral sclerosis).
Establishing the correct diagnosis and baseline disease severity is the prerequisite for appropriate stepwise management.
2
Determine the first-line therapy for knee osteoarthritis according to current clinical guidelines.
Topical nonsteroidal anti-inflammatory drugs (NSAIDs), weight loss, and physical therapy are strongly recommended as the initial interventions.
These conservative measures provide localized and functional benefits while avoiding the gastrointestinal and cardiovascular risks associated with systemic oral medications.
3
Identify the appropriate sequence for escalating medical therapy if initial measures fail.
Oral NSAIDs (or duloxetine) should be trialed next, followed by intra-articular glucocorticoid injections for localized, refractory symptom flares.
Escalation to systemic oral agents and invasive intra-articular procedures should occur sequentially to balance symptom relief with the increasing risks of adverse side effects.
4
Determine the definitive treatment for end-stage, medically refractory disease.
Orthopedic referral for total knee arthroplasty is the final step in the sequence.
Joint replacement surgery is indicated when all non-surgical interventions have failed and the disease severely impairs the patient's quality of life and mobility.

Anahtar Kavram

Stepwise escalation of therapy in knee osteoarthritis prioritizes conservative lifestyle modifications and localized treatments before advancing to systemic medications, intra-articular injections, and ultimately definitive surgery.
Tahmini Süre:1m 0s
Soru 1382Soru →

Match each clinical presentation of a genital ulcer disease with its most appropriate first-line pharmacotherapy.

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Öğeler

A 24-year-old man presents with a single, painless, indurated penile ulcer with a clean base and non-tender bilateral inguinal lymphadenopathy.
A 21-year-old man presents with multiple painful, deep genital ulcers with a purulent base and tender, unilateral, fluctuant inguinal lymph nodes.
A 28-year-old man presents with painful, unilateral inguinal lymphadenopathy with a 'groove sign'. He reports having a small painless genital ulcer a few weeks ago that healed spontaneously.
A 26-year-old woman presents with multiple small, grouped, severely painful vesicles and shallow ulcers on an erythematous base on her labia.

Eşleşmeler

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Cevap

The correct matches align primary syphilis with penicillin, chancroid with azithromycin or ceftriaxone, lymphogranuloma venereum with an extended course of doxycycline, and genital herpes with oral valacyclovir.
Each genital ulcer disease has a distinct clinical phenotype that guides targeted pharmacotherapy. Primary syphilis presents with a painless chancre and is treated with penicillin. Chancroid presents with painful, purulent ulcers and is treated with azithromycin or ceftriaxone. Lymphogranuloma venereum presents with a transient painless ulcer followed by painful buboes and requires 21 days of doxycycline. Genital herpes presents with grouped painful vesicles and is treated with oral antivirals.

Adım Adım Çözüm

1
Analyze the characteristics of the genital ulcer (painful vs. painless, single vs. multiple, clean vs. purulent base) and the associated lymphadenopathy.
Identified the likely pathogens: Treponema pallidum (painless), Haemophilus ducreyi (painful, purulent), Chlamydia trachomatis L1-L3 (transient painless ulcer with severe late adenopathy), and Herpes Simplex Virus (painful vesicles).
Genital ulcer diseases have distinct clinical phenotypes that often allow for a highly accurate presumptive clinical diagnosis.
2
Select the appropriate guideline-directed antimicrobial therapy for each identified pathogen.
Matched T. pallidum with penicillin, H. ducreyi with azithromycin/ceftriaxone, C. trachomatis with doxycycline, and HSV with valacyclovir.
Targeted antimicrobial therapy is essential for curative treatment, symptom resolution, and prevention of transmission.

Anahtar Kavram

Diagnosis and management of genital ulcer diseases based on clinical presentation
Soru 1383Soru →

Match each clinical presentation of infective endocarditis with the most appropriate targeted diagnostic evaluation or therapeutic intervention.

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Öğeler

A 68-year-old patient is diagnosed with native valve endocarditis. Blood cultures yield a non-enterococcal Group D Streptococcus (Streptococcus gallolyticus).
A 52-year-old patient with a mechanical mitral valve placed three years ago presents with acute endocarditis. Blood cultures rapidly grow methicillin-susceptible Staphylococcus aureus.
A 74-year-old patient develops subacute endocarditis following a cystoscopy. Blood cultures grow Enterococcus faecalis demonstrating high-level aminoglycoside resistance.
A 45-year-old patient experiencing homelessness presents with severe body louse infestation and culture-negative endocarditis.

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Cevap

Streptococcus gallolyticus pairs with performing a screening colonoscopy. Staphylococcus aureus prosthetic valve endocarditis pairs with nafcillin, rifampin, and gentamicin. Enterococcus faecalis with high-level aminoglycoside resistance pairs with ampicillin and ceftriaxone. Culture-negative endocarditis in a patient with a body louse infestation pairs with obtaining serology for Bartonella quintana.
Each pairing correctly applies current clinical guidelines for infective endocarditis: S. gallolyticus requires colonoscopy due to a high rate of concomitant colon cancer. S. aureus on a prosthetic valve necessitates a three-drug regimen including rifampin for biofilm penetration. HLAR E. faecalis requires ampicillin plus ceftriaxone for dual beta-lactam synergy. B. quintana is the primary suspect in louse-associated culture-negative endocarditis, requiring serological confirmation.

Adım Adım Çözüm

1
Identify the underlying pathogen and host risk factors in each clinical vignette.
Pathogens identified are S. gallolyticus, S. aureus (prosthetic valve), E. faecalis (with HLAR), and a culture-negative organism associated with body lice.
Management of infective endocarditis is highly tailored to the specific organism, its resistance profile, and whether native or prosthetic material is involved.
2
Determine the unique complication, diagnostic requirement, or therapeutic adjustment for each pathogen.
S. gallolyticus requires GI workup. Prosthetic S. aureus requires biofilm penetration. HLAR Enterococcus requires non-aminoglycoside synergy. Louse-borne culture-negative endocarditis points to Bartonella.
Standard endocarditis protocols fail if these specific nuances (e.g., biofilms, HLAR, occult malignancy) are not addressed.
3
Match the specific pathogen requirements to the listed interventions.
The pairings logically align the microbiologic and epidemiologic clues with the standard-of-care guidelines.
This confirms mastery of pathogen-specific management pathways in infectious diseases.

Anahtar Kavram

Targeted diagnostic and therapeutic management of infective endocarditis based on organism identity, resistance patterns, and host risk factors.
Soru 1384Soru →

A 21-year-old woman with type 1 diabetes mellitus is brought to the emergency department due to lethargy, abdominal pain, and vomiting. She stopped taking her insulin two days ago because she was unable to eat. Her blood pressure is 88/55 mm Hg88/55 \text{ mm Hg}, heart rate is 132/min132\text{/min}, and respiratory rate is 26/min26\text{/min} with deep, sighing breaths. Mucous membranes are markedly dry. Laboratory studies reveal:

Laboratory StudyResult
Serum glucose520 mg/dL520 \text{ mg/dL}
Serum sodium132 mEq/L132 \text{ mEq/L}
Serum potassium2.9 mEq/L2.9 \text{ mEq/L}
Serum bicarbonate10 mEq/L10 \text{ mEq/L}
Arterial pH7.157.15

Arrange the following targeted management steps in the most appropriate chronological sequence according to standard diabetic ketoacidosis (DKA) protocols.

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Cevap

The correct chronological sequence for this patient's management is: 1) Administer a rapid intravenous bolus of 0.9% sodium chloride, 2) Initiate intravenous potassium chloride supplementation, 3) Start a continuous intravenous infusion of regular insulin, and 4) Add 5% dextrose to the maintenance intravenous fluids.
The initial priority in diabetic ketoacidosis (DKA) is restoring intravascular volume with 0.9%0.9\% normal saline to reverse hypovolemic shock and improve renal perfusion. Next, serum potassium must be evaluated. Although patients with DKA have total body potassium depletion, serum levels are often falsely normal or elevated due to extracellular shifts from acidosis and insulin deficiency. In this patient, the serum potassium is already severely low (2.9 mEq/L2.9 \text{ mEq/L}). Because insulin drives potassium into cells, insulin therapy MUST be delayed until serum potassium is restored to at least 3.3 mEq/L3.3 \text{ mEq/L} to avoid fatal arrhythmias. Once potassium is appropriately replaced, an intravenous regular insulin infusion is started to halt ketogenesis. Finally, when blood glucose levels fall to approximately 200 mg/dL200 \text{ mg/dL}, 5%5\% dextrose is added to the intravenous fluids. This prevents hypoglycemia while allowing the continuous insulin infusion to remain active until the anion gap successfully closes.

Adım Adım Çözüm

1
Assess hemodynamic status and establish immediate priorities.
Patient is in hypovolemic shock (BP 88/55 mm Hg88/55 \text{ mm Hg}). The first step must be fluid resuscitation with 0.9%0.9\% normal saline.
Restoring intravascular volume improves renal perfusion and begins the process of lowering serum osmolality.
2
Evaluate the initial serum potassium level before giving insulin.
Potassium is 2.9 mEq/L2.9 \text{ mEq/L}, which is below the critical threshold of 3.3 mEq/L3.3 \text{ mEq/L}.
Insulin drives potassium intracellularly. Giving insulin now would cause life-threatening hypokalemia. Potassium repletion is the immediate next step.
3
Determine the timing for insulin administration.
Intravenous regular insulin can only be started after serum potassium is confirmed to be >3.3 mEq/L> 3.3 \text{ mEq/L}.
Insulin is required to halt ketogenesis and close the anion gap, but must be timed safely relative to potassium correction.
4
Plan for the transition phase of DKA management.
Dextrose (5%5\%) must be added to the intravenous fluids once serum glucose falls below 200 mg/dL200 \text{ mg/dL}.
To prevent hypoglycemia while continuing the insulin drip required to resolve the underlying ketoacidosis.

Anahtar Kavram

The acute management sequence of Diabetic Ketoacidosis (DKA) strictly prioritizes fluid resuscitation, followed by assessment and correction of severe hypokalemia prior to the initiation of insulin therapy.
Soru 1385Soru →

During a weekend shift at the acute care clinic, a 6969-year-old male with a history of castration-resistant prostate cancer is evaluated for escalating mid-thoracic back pain over the past three days. He describes a new sensation of heaviness in both legs that has progressively impaired his ability to walk unassisted. Additionally, he reports an episode of involuntary urinary dribbling earlier this morning. Current medications include leuprolide and denosumab. Vital signs are temperature 37.1∘C37.1^{\circ}\text{C} (98.8∘F98.8^{\circ}\text{F}), blood pressure 142/86 mm Hg142/86 \text{ mm Hg}, pulse 88/min88/\text{min}, and respiratory rate 14/min14/\text{min}. Physical examination reveals exquisite tenderness to percussion over the T10T10 spinous process. Neurologic evaluation demonstrates 3/53/5 muscle strength in bilateral lower extremities, symmetrically hyperactive patellar reflexes, and diminished pinprick sensation below the umbilicus. Digital rectal examination reveals decreased anal sphincter tone. Which of the following is the most appropriate initial step in the management of this patient?

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Cevap: Administer intravenous dexamethasone

Cevap

Administer intravenous dexamethasone
The correct answer is to administer intravenous dexamethasone. This patient's presentation of escalating back pain, lower extremity weakness, sensory level deficit, upper motor neuron signs (hyperreflexia), and bowel/bladder dysfunction in the setting of advanced prostate cancer is highly indicative of malignant epidural spinal cord compression (MESCC). MESCC is a true oncologic emergency. The absolute most critical initial step in management is the immediate administration of high-dose intravenous corticosteroids (such as dexamethasone). Corticosteroids rapidly reduce the vasogenic edema surrounding the epidural tumor, thereby decreasing pressure on the spinal cord, restoring blood flow, and preserving neurologic function. This empirical therapy must be initiated instantly upon clinical suspicion, even before diagnostic imaging is performed, to prevent irreversible paralysis.

Adım Adım Çözüm

1
Identify the clinical syndrome
The patient has progressive back pain, lower extremity weakness, sensory level at T10T10, upper motor neuron signs, and autonomic dysfunction (urinary retention).
These are the classic neurologic findings of a spinal cord compression.
2
Determine the most likely etiology
Given the established history of advanced prostate cancer and lack of infectious signs, this presentation is highly suspicious for malignant epidural spinal cord compression (MESCC).
Prostate cancer frequently metastasizes to the axial skeleton, placing the patient at high risk for epidural space invasion.
3
Select the most urgent initial intervention
Intravenous glucocorticoids (such as dexamethasone) must be administered immediately.
Corticosteroids decrease peritumoral vasogenic edema, relieving mechanical pressure on the spinal cord and preventing irreversible ischemic injury. This life-saving medical therapy must precede all diagnostic imaging.

Anahtar Kavram

Empirical management of Malignant Epidural Spinal Cord Compression (MESCC)
Soru 1386Soru →

A 62-year-old man is evaluated in the hospital on hospital day 3. He was initially admitted for high fever and rigors. His past medical history is significant for end-stage renal disease requiring hemodialysis via a right internal jugular tunneled catheter. Upon admission, peripheral and catheter-drawn blood cultures were obtained, and he was started on empiric antimicrobial therapy with intravenous vancomycin and piperacillin-tazobactam. Today, his temperature is 37.2°C (99.0°F), blood pressure is 128/76 mmHg, and heart rate is 82/min. The admission blood cultures are now positive for Staphylococcus aureus in 4 out of 4 bottles. Susceptibility testing reveals the isolate is resistant to penicillin, but susceptible to oxacillin, cefazolin, and vancomycin. A review of the patient's medical record indicates a documented allergy to amoxicillin, which the patient describes as a 'flat, red skin rash' that occurred several days into a treatment course 10 years ago, without associated pruritus, facial swelling, or difficulty breathing. Which of the following is the most appropriate modification to his current pharmacotherapy?

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Cevap: Transition to intravenous cefazolin monotherapy

Cevap

Transition to intravenous cefazolin monotherapy.
The patient has Methicillin-Susceptible Staphylococcus aureus (MSSA) bacteremia, as evidenced by the susceptibility to oxacillin. The standard of care for MSSA endovascular infections and bacteremia dictates the use of a narrow-spectrum beta-lactam, such as an anti-staphylococcal penicillin (nafcillin, oxacillin) or a first-generation cephalosporin (cefazolin). These agents are definitively superior to vancomycin, providing faster bacterial clearance, lower rates of relapse, and reduced mortality. The patient's reported amoxicillin allergy—a delayed, flat, non-itchy rash—is characteristic of a non-IgE mediated (Type IV) mild hypersensitivity or a viral-antibiotic interaction, not true anaphylaxis. Furthermore, cefazolin has a unique R1 side chain that does not cross-react with other penicillins or cephalosporins. Therefore, it is entirely safe and represents the optimal stewardship choice for definitive therapy.

Adım Adım Çözüm

1
Interpret the blood culture and susceptibility results.
The pathogen is Staphylococcus aureus that is susceptible to oxacillin, confirming it is Methicillin-Susceptible Staphylococcus aureus (MSSA).
Accurate pathogen identification and resistance profiling dictate the definitive antimicrobial choice.
2
Determine the optimal class of antibiotics for MSSA bacteremia.
Anti-staphylococcal penicillins (e.g., nafcillin, oxacillin) or first-generation cephalosporins (e.g., cefazolin) are the superior agents.
Clinical data consistently demonstrate that beta-lactams yield faster clearance and lower mortality rates for MSSA bacteremia compared to vancomycin.
3
Evaluate the patient's reported penicillin allergy and assess cross-reactivity risk.
The patient describes a delayed, non-pruritic maculopapular rash, which is a mild, non-IgE mediated reaction. Cefazolin has a distinct R1 side chain and negligible cross-reactivity with penicillins.
Understanding allergy phenotypes prevents unnecessary avoidance of first-line therapies. A mild delayed rash is not a contraindication to cefazolin.

Anahtar Kavram

For Methicillin-Susceptible Staphylococcus aureus (MSSA) bacteremia, narrow-spectrum beta-lactams (like cefazolin or nafcillin) are superior to vancomycin. A history of a mild, non-IgE mediated delayed rash to penicillin is not a contraindication to cefazolin therapy.
Soru 1387Soru →

A 4545-year-old man is brought to the emergency department by his sister due to altered mental status. She states that he has a history of alcohol use disorder and was found confused in his apartment with an empty bottle of antifreeze nearby. Laboratory studies show:

LabValue
Serum sodium140 mEq/L140 \text{ mEq/L}
Serum potassium4.0 mEq/L4.0 \text{ mEq/L}
Serum chloride102 mEq/L102 \text{ mEq/L}
Serum bicarbonate12 mEq/L12 \text{ mEq/L}
Blood urea nitrogen (BUN)28 mg/dL28 \text{ mg/dL}
Serum glucose180 mg/dL180 \text{ mg/dL}
Measured serum osmolality325 mOsm/kg H2O325 \text{ mOsm/kg H}_2\text{O}

Based on these laboratory results, what is this patient's calculated osmolar gap? (Provide the exact numerical value)

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Cevap: 25

Cevap

The calculated osmolar gap is 25.
The patient has an elevated measured osmolality due to the ingestion of ethylene glycol (antifreeze). The calculated osmolality is 300 mOsm/kg H2O300 \text{ mOsm/kg H}_2\text{O}, derived from the formula 2×Na++Glucose18+BUN2.82 \times \text{Na}^+ + \frac{\text{Glucose}}{18} + \frac{\text{BUN}}{2.8}. Subtracting this calculated value from the measured osmolality of 325 mOsm/kg H2O325 \text{ mOsm/kg H}_2\text{O} gives an osmolar gap of 2525. An elevated osmolar gap is a hallmark of toxic alcohol ingestion.

Adım Adım Çözüm

1
Calculate the estimated serum osmolality using the standard formula.
Calculated Osmolality = 2×140+18018+282.8=280+10+10=300 mOsm/kg H2O2 \times 140 + \frac{180}{18} + \frac{28}{2.8} = 280 + 10 + 10 = 300 \text{ mOsm/kg H}_2\text{O}.
The osmolar gap is the difference between measured and calculated osmolality. To find the gap, the calculated osmolality must first be determined from serum sodium, glucose, and BUN.
2
Subtract the calculated osmolality from the measured osmolality.
325−300=25325 - 300 = 25.
This yields the osmolar gap, which represents the presence of unmeasured osmotically active substances (in this case, ethylene glycol from antifreeze).

Anahtar Kavram

The osmolar gap is calculated by subtracting the calculated serum osmolality (2×Na++Glucose18+BUN2.82 \times \text{Na}^+ + \frac{\text{Glucose}}{18} + \frac{\text{BUN}}{2.8}) from the measured serum osmolality. An elevated osmolar gap (>10 mOsm/kg H2O>10 \text{ mOsm/kg H}_2\text{O}) typically indicates the presence of toxic alcohols.
Tahmini Süre:1m 0s
Soru 1388Soru →

A 45-year-old woman is evaluated in the intensive care unit on the second day of induction chemotherapy for newly diagnosed high-grade Burkitt lymphoma. Over the past 8 hours, her urine output has significantly decreased. She reports mild nausea and generalized weakness. Her temperature is 37.1∘C37.1^\circ\text{C} (98.8∘F98.8^\circ\text{F}), blood pressure is 110/70 mmHg110/70\text{ mmHg}, and pulse is 88/min88/\text{min}. A stat laboratory panel shows the following results:

Laboratory TestResultReference Range
Potassium6.8 mEq/L6.8\text{ mEq/L}3.5−5.0 mEq/L3.5-5.0\text{ mEq/L}
Calcium6.9 mg/dL6.9\text{ mg/dL}8.4−10.2 mg/dL8.4-10.2\text{ mg/dL}
Phosphorus7.8 mg/dL7.8\text{ mg/dL}2.5−4.5 mg/dL2.5-4.5\text{ mg/dL}
Uric acid14.2 mg/dL14.2\text{ mg/dL}2.4−6.0 mg/dL2.4-6.0\text{ mg/dL}
Creatinine2.6 mg/dL2.6\text{ mg/dL}0.6−1.1 mg/dL0.6-1.1\text{ mg/dL}

An electrocardiogram (ECG) reveals tall, peaked T waves with a shortened QT interval. Which of the following is the most appropriate next step in the management of this patient?

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Cevap: Administer intravenous calcium gluconate

Cevap

Administer intravenous calcium gluconate
The correct answer is to administer intravenous calcium gluconate. This patient has classic Tumor Lysis Syndrome (TLS), an oncologic emergency characterized by the massive release of intracellular contents following chemotherapy. The most immediately life-threatening complication of TLS is severe hyperkalemia, which this patient has developed along with concerning ECG changes (peaked T waves). In any patient with severe hyperkalemia and associated ECG abnormalities, the absolute first step in management is to stabilize the myocardial cell membrane with intravenous calcium (gluconate or chloride) to prevent fatal ventricular arrhythmias. Once the myocardium is stabilized, subsequent therapies can be initiated to shift potassium intracellularly (e.g., insulin and glucose) and remove it from the body, alongside targeted TLS treatments like rasburicase.

Adım Adım Çözüm

1
Identify the underlying clinical syndrome based on the presentation and labs.
The patient has Tumor Lysis Syndrome (TLS) characterized by hyperuricemia, hyperkalemia, hyperphosphatemia, hypocalcemia, and acute kidney injury following chemotherapy for a rapidly proliferating lymphoma.
Recognizing TLS provides the necessary context for anticipating severe metabolic derangements.
2
Prioritize the laboratory abnormalities to identify the most immediate threat to the patient's life.
The most dangerous abnormality is the severe hyperkalemia (6.8 mEq/L6.8\text{ mEq/L}) with corresponding ECG changes (peaked T waves).
Hyperkalemia with ECG changes indicates imminent risk of lethal ventricular arrhythmias and cardiac arrest.
3
Determine the most rapid and effective intervention for the primary threat.
Intravenous calcium gluconate must be administered immediately.
Calcium directly antagonizes the effects of potassium on the myocardial cell membrane, providing instant cardioprotection while other therapies to lower serum potassium and uric acid are prepared.

Anahtar Kavram

In Tumor Lysis Syndrome complicated by severe hyperkalemia with ECG changes, immediate myocardial membrane stabilization with intravenous calcium is the paramount first step in management.
Tahmini Süre:1m 15s
Soru 1389Soru →

A 74-year-old man is evaluated in the surgical telemetry unit on postoperative day 4 following an open cholecystectomy and common bile duct exploration. The nursing staff requested a review because his urine output has decreased to 250 mL250 \text{ mL} over the last 24 hours, and he has become increasingly confused and short of breath. His medical history includes hypertension, type 2 diabetes mellitus, and a 40-pack-year smoking history. Temperature is 37.6∘C37.6^\circ\text{C} (99.7∘F99.7^\circ\text{F}), blood pressure is 155/92 mm Hg155/92 \text{ mm Hg}, pulse is 112/min112/\text{min}, and respirations are 26/min26/\text{min}. Oxygen saturation is 88%88\% on room air. Physical examination shows jugular venous distention 10 cm10 \text{ cm} above the sternal angle. Auscultation of the lungs reveals bilateral basilar crackles. The abdomen is soft and non-tender, with intact surgical staples and no erythema. Bilateral 2+2+ pitting edema is present in the lower extremities.

Laboratory studies show:
Serum sodium: 134 mEq/L134 \text{ mEq/L}
Serum potassium: 5.2 mEq/L5.2 \text{ mEq/L}
Serum chloride: 98 mEq/L98 \text{ mEq/L}
Serum bicarbonate: 14 mEq/L14 \text{ mEq/L}
Blood urea nitrogen: 68 mg/dL68 \text{ mg/dL}
Serum creatinine: 3.1 mg/dL3.1 \text{ mg/dL} (baseline 1.1 mg/dL1.1 \text{ mg/dL})

Arterial blood gas (room air):
pH: 7.247.24
PaCO2: 42 mm Hg42 \text{ mm Hg}
PaO2: 58 mm Hg58 \text{ mm Hg}

Which of the following is the most accurate characterization of this patient's acid-base status and the most appropriate next step in management?

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Cevap: Mixed high anion gap metabolic acidosis and respiratory acidosis; administer intravenous furosemide

Cevap

Mixed high anion gap metabolic acidosis and respiratory acidosis; administer intravenous furosemide
This patient presents with acute kidney injury, severe volume overload, and a complex acid-base derangement. The low pH (7.247.24) and low serum bicarbonate (14 mEq/L14 \text{ mEq/L}) establish a primary metabolic acidosis. The anion gap is elevated at 2222 (134−(98+14)134 - (98 + 14)), pointing to a high anion gap metabolic acidosis, likely from retention of unmeasured uremic acids due to his acute kidney injury. To determine if respiratory compensation is adequate, Winter's formula must be applied: Expected PaCO2=1.5×[HCO3−]+8±2\text{PaCO}_2 = 1.5 \times [\text{HCO}_3^-] + 8 \pm 2. For a bicarbonate of 14 mEq/L14 \text{ mEq/L}, the expected PaCO2\text{PaCO}_2 is 2727 to 31 mm Hg31 \text{ mm Hg}. The patient's actual PaCO2\text{PaCO}_2 is 42 mm Hg42 \text{ mm Hg}, which is inappropriately high, indicating a concurrent primary respiratory acidosis. Clinically, this patient is in acute decompensated heart failure (ADHF) with pulmonary edema (crackles, hypoxia) and cardiorenal syndrome. The pulmonary edema impairs gas exchange, leading to CO2\text{CO}_2 retention and respiratory acidosis. The most appropriate immediate management for ADHF with pulmonary edema and cardiorenal acute kidney injury is diuresis with intravenous furosemide to decrease preload, relieve pulmonary congestion, and improve renal hemodynamics.

Adım Adım Çözüm

1
Identify the primary acid-base disorder using pH and bicarbonate levels.
The pH is 7.24 (acidemia) and serum bicarbonate is 14 mEq/L (low), indicating a primary metabolic acidosis.
Establishing the primary disturbance is required to determine the direction of the expected compensatory response.
2
Calculate the serum anion gap.
Anion Gap = Na - (Cl + HCO3) = 134 - (98 + 14) = 22 mEq/L. This is a high anion gap metabolic acidosis.
Differentiating between normal and high anion gap acidosis narrows the differential diagnosis (in this case, uremia from acute kidney injury).
3
Calculate the expected respiratory compensation using Winter's formula.
Expected PaCO2 = (1.5 x 14) + 8 = 29 (range 27-31 mm Hg).
Winter's formula determines if the pulmonary response to metabolic acidosis is appropriate or if a secondary respiratory disorder exists.
4
Compare the actual PaCO2 to the expected PaCO2.
The actual PaCO2 is 42 mm Hg, which is significantly higher than the expected range (27-31 mm Hg), confirming a superimposed primary respiratory acidosis.
An inappropriately elevated PaCO2 in the setting of metabolic acidosis indicates a mixed disorder (metabolic acidosis + respiratory acidosis).
5
Integrate clinical findings to determine the underlying etiology and next best step.
The patient exhibits signs of severe volume overload (hypertension, JVD, crackles, edema) causing cardiorenal syndrome (AKI) and pulmonary edema (respiratory acidosis). The correct intervention is intravenous furosemide.
Loop diuretics decrease preload, relieve pulmonary congestion, and can improve renal hemodynamics in acute decompensated heart failure.

Anahtar Kavram

Diagnosis of mixed acid-base disorders using Winter's formula and management of cardiorenal syndrome.
Tahmini Süre:2m 0s
Soru 1390Soru →

A 62-year-old man is evaluated in the intensive care unit on day 4 of an admission for severe urosepsis. He initially required mechanical ventilation and vasopressor support but is now hemodynamically stable and was extubated yesterday. He has a history of hypertension and benign prostatic hyperplasia. His medications include amlodipine, tamsulosin, and intravenous antibiotics. He has no history of thyroid disease. His temperature is 37.2°C (99.0°F), blood pressure is 118/76 mm Hg, and pulse is 82/min. Physical examination reveals clear lungs and a normal-sized, non-tender thyroid gland.

Laboratory studies show:

TestResultReference Range
Thyroid-stimulating hormone (TSH)1.1 µU/mL0.4–4.0 µU/mL
Free thyroxine (T4)1.2 ng/dL0.9–1.7 ng/dL
Total triiodothyronine (T3)50 ng/dL80–200 ng/dL

Which of the following is the most likely mechanism responsible for this patient's thyroid laboratory findings?

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Cevap: Decreased peripheral conversion of thyroxine to triiodothyronine

Cevap

Decreased peripheral conversion of thyroxine to triiodothyronine (Euthyroid sick syndrome)
This patient's clinical picture of a severe systemic illness (urosepsis requiring ICU admission) combined with a low total T3, normal free T4, and normal TSH is classic for euthyroid sick syndrome, also known as non-thyroidal illness syndrome. In the setting of severe physiologic stress (such as sepsis, trauma, or prolonged starvation), the body decreases the activity of 5'-deiodinase, the enzyme responsible for the peripheral conversion of T4 (thyroxine) to the more active T3 (triiodothyronine). Concurrently, 5-deiodinase activity often increases, shunting T4 to the inactive metabolite reverse T3 (rT3). This is thought to be an adaptive mechanism to reduce metabolic rate and conserve energy during acute, severe illness. Thyroid hormone replacement is not indicated, and laboratory values typically normalize once the underlying illness resolves.

Adım Adım Çözüm

1
Evaluate the patient's clinical context.
The patient is recovering from a severe systemic illness (urosepsis requiring ICU admission).
Severe physiologic stress alters normal metabolic pathways, including thyroid hormone metabolism.
2
Interpret the thyroid function tests.
The patient has a normal TSH, normal free T4, and a selectively low total T3.
Identifying the specific pattern of thyroid laboratory abnormalities is required to determine the underlying etiology.
3
Synthesize the clinical history with the laboratory findings to identify the diagnosis and its mechanism.
The pattern of low T3 with normal T4 and TSH in an ICU patient confirms euthyroid sick syndrome (non-thyroidal illness syndrome), driven by decreased 5'-deiodinase activity.
During severe illness, the body adapts by reducing the conversion of prohormone (T4) to active hormone (T3) to conserve energy.

Anahtar Kavram

Euthyroid sick syndrome (non-thyroidal illness syndrome)
Soru 1391Soru →

Match each clinical presentation of an adverse drug effect with the most likely responsible antineoplastic or targeted therapy agent.

Soldaki öğeye tıklayın, sonra eşleşen sağdaki öğeye tıklayın

Öğeler

A 42-year-old woman receiving targeted therapy for HER2-positive breast cancer develops an asymptomatic decline in left ventricular ejection fraction that is independent of cumulative dose.
A 38-year-old man receiving a platinum-based regimen for a metastatic non-seminomatous germ cell tumor develops high-frequency sensorineural hearing loss and a rising serum creatinine.
A 62-year-old man with chronic myeloid leukemia treated with a tyrosine kinase inhibitor presents with progressive dyspnea; imaging reveals new-onset exudative bilateral pleural effusions.
A 68-year-old woman receiving consolidation chemotherapy for acute myeloid leukemia acutely develops nystagmus, dysmetria, and a broad-based gait.
A 55-year-old man on adjuvant chemotherapy for stage III colon cancer complains of severe distal dysesthesia and throat tightness that is consistently triggered by drinking cold beverages.

Eşleşmeler

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Cevap

The correct matches are: Reversible LVEF decline with Trastuzumab; Hearing loss and renal injury with Cisplatin; Pleural effusions with Dasatinib; Acute cerebellar toxicity with Cytarabine; and Cold-induced neuropathy with Oxaliplatin.
Each antineoplastic agent has a well-defined toxicity profile. Trastuzumab causes reversible cardiotoxicity. Cisplatin causes ototoxicity and nephrotoxicity. Dasatinib can cause significant fluid retention, particularly pleural effusions. High-dose cytarabine causes cerebellar toxicity. Oxaliplatin causes acute cold-induced sensory neuropathy.

Adım Adım Çözüm

1
Evaluate the cardiac toxicity profile.
The asymptomatic, non-dose-dependent, and typically reversible LVEF decline points to Trastuzumab.
Differentiating Type I (anthracycline, dose-dependent, irreversible) from Type II (trastuzumab) cardiotoxicity is critical in oncology management.
2
Evaluate the ototoxicity and nephrotoxicity profile.
The combination of sensorineural hearing loss and rising creatinine points to Cisplatin.
Platinum-based alkylating-like agents have distinct toxicities; cisplatin is the most ototoxic and nephrotoxic of the group.
3
Evaluate the respiratory toxicity in CML.
Exudative pleural effusions in a patient on a tyrosine kinase inhibitor strongly point to Dasatinib.
While imatinib commonly causes periorbital edema, dasatinib specifically causes pleural effusions and pulmonary hypertension.
4
Evaluate the acute neurotoxicity in AML treatment.
Acute onset of nystagmus and ataxia during consolidation therapy identifies Cytarabine cerebellar toxicity.
High-dose regimens of cytarabine require routine neurological checks before each dose due to this specific risk.
5
Evaluate the peripheral neuropathy triggered by cold.
Cold-exacerbated dysesthesia and throat tightness identify Oxaliplatin.
Unlike the chronic stocking-glove neuropathy of vinca alkaloids or taxanes, oxaliplatin causes this unique acute cold-induced phenomenon.

Anahtar Kavram

Adverse effect profiles of antineoplastic agents
Tahmini Süre:1m 30s
Soru 1392Soru →

Emergency medical services bring a 68-year-old man to the hospital after his daughter found him lethargic and struggling to breathe. For the past 48 hours, he has experienced a fever and a worsening productive cough. His medical history is significant for severe chronic obstructive pulmonary disease (COPD), hypertension, and type 2 diabetes mellitus. His daily medications include tiotropium, lisinopril, and empagliflozin.

Vital signs are:
Temperature: 38.2°C (100.8°F)
Blood pressure: 110/65 mm Hg
Pulse: 118/min
Respirations: 26/min
Oxygen saturation: 86% on room air

Physical examination reveals a somnolent but arousable patient. Lung auscultation demonstrates diffuse wheezing and right lower lobe crackles with a prolonged expiratory phase.

Laboratory results are as follows:

ParameterResult
Sodium140 mEq/L
Potassium4.6 mEq/L
Chloride104 mEq/L
Bicarbonate12 mEq/L
Blood urea nitrogen32 mg/dL
Creatinine1.4 mg/dL
Glucose195 mg/dL
Albumin4.0 g/dL

Arterial blood gas analysis on room air reveals:

ParameterResult
pH7.12
pCO2_238 mm Hg
pO2_256 mm Hg

Which of the following best characterizes this patient's acid-base status?

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Cevap: High anion gap metabolic acidosis with concurrent respiratory acidosis

Cevap

High anion gap metabolic acidosis with concurrent respiratory acidosis
This patient's acid-base status is evaluated in a stepwise fashion. First, the arterial pH is 7.12, indicating acidemia. The low serum bicarbonate (12 mEq/L) confirms a metabolic acidosis. Second, the anion gap must be calculated: AG=Na+−(Cl−+HCO3−)=140−(104+12)=24AG = Na^+ - (Cl^- + HCO_3^-) = 140 - (104 + 12) = 24 mEq/L. A normal anion gap is 10-14 mEq/L, so the patient has a high anion gap metabolic acidosis (HAGMA), which in this clinical scenario is likely secondary to sepsis or euglycemic diabetic ketoacidosis from empagliflozin use.

Next, to evaluate for mixed acid-base disorders, Winter's formula (pCO2=1.5×[HCO3−]+8±2pCO_2 = 1.5 \times [HCO_3^-] + 8 \pm 2) is used to determine the expected respiratory compensation. For this patient, the expected pCO2=1.5×12+8=26±2pCO_2 = 1.5 \times 12 + 8 = 26 \pm 2 mm Hg. The patient's actual measured pCO2pCO_2 is 38 mm Hg. Because the actual pCO2pCO_2 is significantly higher than the expected range of 24-28 mm Hg, there is relative CO2CO_2 retention, confirming the presence of a concurrent primary respiratory acidosis. This is clinically consistent with a patient experiencing a COPD exacerbation and pneumonia, leading to respiratory fatigue and hypoventilation.

Adım Adım Çözüm

1
Calculate the anion gap to determine the primary metabolic disturbance.
AG = Na+−(Cl−+HCO3−)=140−(104+12)=24Na^+ - (Cl^- + HCO_3^-) = 140 - (104 + 12) = 24 mEq/L.
An anion gap > 12 mEq/L confirms the presence of a high anion gap metabolic acidosis (HAGMA).
2
Apply Winter's formula to determine if respiratory compensation is appropriate.
Expected pCO2=1.5×[HCO3−]+8±2=1.5×12+8±2=26±2pCO_2 = 1.5 \times [HCO_3^-] + 8 \pm 2 = 1.5 \times 12 + 8 \pm 2 = 26 \pm 2 mm Hg.
This establishes the target pCO2pCO_2 range (24-28 mm Hg) the lungs should achieve to compensate for the metabolic acidosis.
3
Compare the actual pCO2pCO_2 to the expected pCO2pCO_2 calculated from Winter's formula.
The actual pCO2pCO_2 is 38 mm Hg, which is > 28 mm Hg.
An actual pCO2pCO_2 that is higher than the expected calculated range indicates a concurrent respiratory acidosis (relative CO2CO_2 retention).

Anahtar Kavram

In patients with metabolic acidosis, Winter's formula is essential to determine whether the respiratory response is adequate; an actual pCO2 higher than the expected range indicates a concurrent respiratory acidosis.
Soru 1393Soru →

A 34-year-old woman comes to the clinic for an annual health maintenance evaluation. She mentions feeling a bit fatigued lately but otherwise feels well. She has no history of neck radiation, surgery, or significant medical conditions. Her vital signs are within normal limits. Physical examination reveals a normal-sized thyroid gland without palpable nodules.

Laboratory studies are obtained with the following results:

Thyroid-stimulating hormone (TSH): 6.8 \muU/mL6.8 \text{ \mu U/mL} (Normal: 0.5−5.0 \muU/mL0.5 - 5.0 \text{ \mu U/mL})
Free thyroxine (T4): 1.4 ng/dL1.4 \text{ ng/dL} (Normal: 0.9−1.7 ng/dL0.9 - 1.7 \text{ ng/dL})

Which of the following is the most likely diagnosis?

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Cevap: Subclinical hypothyroidism

Cevap

Subclinical hypothyroidism
The correct diagnosis is subclinical hypothyroidism. This condition is biochemically defined by an elevated thyroid-stimulating hormone (TSH) level occurring alongside a normal serum free thyroxine (T4) level. Patients may be completely asymptomatic or have very mild, non-specific symptoms such as fatigue. In this vignette, the patient's TSH of 6.8 \muU/mL6.8 \text{ \mu U/mL} is elevated, but her free T4 is clearly within normal limits, making this the only accurate diagnosis.

Adım Adım Çözüm

1
Evaluate the patient's Thyroid-stimulating hormone (TSH) level.
The TSH is elevated at 6.8 \muU/mL6.8 \text{ \mu U/mL}.
TSH is the most sensitive initial screening test for primary thyroid dysfunction.
2
Evaluate the patient's Free thyroxine (T4) level.
The Free T4 is within the normal range at 1.4 ng/dL1.4 \text{ ng/dL}.
Free T4 distinguishes between overt and subclinical thyroid disease when TSH is abnormal.
3
Synthesize the laboratory findings to determine the diagnosis.
An elevated TSH paired with a normal Free T4 indicates a subclinical hypothyroid state.
The thyroid gland is producing adequate T4, but it requires higher-than-normal TSH stimulation from the pituitary to do so.

Anahtar Kavram

Subclinical hypothyroidism is defined biochemically by an elevated TSH level in the presence of a normal free T4 level.
Soru 1394Soru →

A 72-year-old man is brought to the emergency department by his daughter due to severe shortness of breath and an inability to lie flat in bed for the past 33 days. He also reports a persistent nonproductive cough. His medical history is significant for chronic obstructive pulmonary disease (COPD), hypertension, stage 3 chronic kidney disease, and a nonfunctioning pituitary macroadenoma that was surgically resected 55 years ago. His current medications include a daily tiotropium inhaler and amlodipine.

His temperature is 37.1∘37.1^\circ C (98.8∘98.8^\circ F), blood pressure is 165/95165/95 mm Hg, pulse is 102102/min, and respiratory rate is 2424/min. Pulse oximetry shows 88%88\% on room air. Physical examination reveals an elevated jugular venous pressure of 1010 cm H 2_2 O. Lung auscultation demonstrates bilateral crackles in the lower lung fields and a prolonged expiratory phase with scattered wheezes. Cardiac examination reveals a regular tachycardia and a prominent S 3_3 gallop. There is 2+2+ pitting edema in the bilateral lower extremities.

Laboratory StudyResultReference Range
Leukocyte count7,5007,500/mm3^34,000−11,0004,000-11,000/mm3^3
Serum sodium136136 mEq/L135−145135-145 mEq/L
Serum potassium4.24.2 mEq/L3.5−5.03.5-5.0 mEq/L
Serum bicarbonate1818 mEq/L22−2822-28 mEq/L
Blood urea nitrogen3535 mg/dL8−208-20 mg/dL
Serum creatinine1.71.7 mg/dL0.7−1.30.7-1.3 mg/dL
Thyroid-stimulating hormone (TSH)1.51.5 μ\muU/mL0.4−4.20.4-4.2 μ\muU/mL
Free T40.60.6 ng/dL0.9−1.70.9-1.7 ng/dL
Arterial Blood Gas (Room Air)ResultReference Range
pH7.377.377.35−7.457.35-7.45
pCO2_23232 mm Hg35−4535-45 mm Hg
pO2_25858 mm Hg75−10575-105 mm Hg

A chest radiograph displays cardiomegaly, bilateral pleural effusions, and prominent interstitial markings without focal consolidation. Which of the following is the most appropriate next step in management for this patient?

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Cevap: Administer intravenous furosemide

Cevap

The correct answer is to administer intravenous furosemide.
The patient's presentation of progressive orthopnea, elevated JVP, an S3 gallop, basilar crackles, and bilateral pitting edema is pathognomonic for acute decompensated heart failure (ADHF). The chest radiograph further supports this with cardiomegaly, pleural effusions, and interstitial edema. The most appropriate immediate next step in management is the administration of a loop diuretic, such as intravenous furosemide. This will rapidly decrease intravascular volume and right heart preload, which promptly relieves pulmonary congestion and improves the work of breathing.

Adım Adım Çözüm

1
Evaluate the clinical presentation and physical examination findings.
The patient has severe orthopnea, elevated jugular venous pressure, an S3 gallop, crackles, and peripheral edema.
These findings are hallmark signs of volume overload and acute decompensated heart failure (ADHF), overriding the diagnosis of a COPD exacerbation despite the presence of wheezing (cardiac asthma).
2
Analyze the laboratory and radiographic data to rule out competing diagnoses.
The chest radiograph confirms cardiomegaly and pulmonary edema without consolidation. The ABG shows a compensated metabolic acidosis with mild primary respiratory alkalosis, and thyroid labs show central hypothyroidism.
This confirms ADHF, rules out pneumonia (no consolidation/leukocytosis), and reveals underlying chronic issues that do not require immediate, life-saving acute intervention.
3
Select the most appropriate acute therapeutic intervention.
Intravenous furosemide is chosen.
Intravenous loop diuretics rapidly reduce intravascular volume and preload, quickly reversing pulmonary congestion and improving the patient's respiratory status.

Anahtar Kavram

Patients with acute decompensated heart failure can present with wheezing ('cardiac asthma'); management relies on rapid diuresis with intravenous loop diuretics, guided by signs of volume overload such as JVD, S3 gallop, and characteristic radiographic findings.
Tahmini Süre:1m 30s
Soru 1395Soru →

A 64-year-old woman is evaluated in the clinic following routine laboratory testing that revealed hypercalcemia. She has no symptoms of fatigue, abdominal pain, bone pain, or cognitive changes. Her medical history is significant for essential hypertension and osteopenia. Her medications include chlorthalidone and cholecalciferol. Blood pressure is 132/82 mm Hg, and pulse is 72/min. Physical examination is unremarkable.

Laboratory results are as follows:

TestResultReference Range
Calcium11.2 mg/dL11.2 \text{ mg/dL}8.4−10.2 mg/dL8.4-10.2 \text{ mg/dL}
Phosphorus2.6 mg/dL2.6 \text{ mg/dL}2.5−4.5 mg/dL2.5-4.5 \text{ mg/dL}
Intact parathyroid hormone78 pg/mL78 \text{ pg/mL}15−65 pg/mL15-65 \text{ pg/mL}
25-hydroxyvitamin D36 ng/mL36 \text{ ng/mL}20−50 ng/mL20-50 \text{ ng/mL}
Creatinine0.8 mg/dL0.8 \text{ mg/dL}0.6−1.2 mg/dL0.6-1.2 \text{ mg/dL}
24-hour urine calcium85 mg85 \text{ mg}100−300 mg100-300 \text{ mg}
24-hour urine creatinine1000 mg1000 \text{ mg}800−1800 mg800-1800 \text{ mg}

The calculated calcium-to-creatinine clearance ratio is 0.0060.006.

Which of the following is the most appropriate next step in management?

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Cevap: Discontinue chlorthalidone and repeat laboratory testing

Cevap

The most appropriate next step is to discontinue chlorthalidone and repeat the laboratory testing.
The most appropriate next step in management is to discontinue the thiazide diuretic (chlorthalidone) and repeat the laboratory testing in several weeks. This patient presents with PTH-dependent hypercalcemia (elevated serum calcium with an unsuppressed, elevated PTH). The primary differential for PTH-dependent hypercalcemia includes primary hyperparathyroidism, familial hypocalciuric hypercalcemia (FHH), and medication-induced hypercalcemia (e.g., lithium, thiazide diuretics). To differentiate between these, a 24-hour urine calcium and a calcium-to-creatinine clearance ratio (CCCR) are calculated. A CCCR of <0.01< 0.01 indicates profound hypocalciuria. While this is the classic biochemical hallmark of FHH, thiazide diuretics act on the distal convoluted tubule to increase calcium reabsorption, producing an identical laboratory profile. Therefore, before pursuing genetic testing for FHH or evaluating for primary hyperparathyroidism, the confounding medication must be stopped, and the calcium profile reassessed to determine the true underlying physiology.

Adım Adım Çözüm

1
Analyze the serum calcium and intact PTH levels.
The patient has hypercalcemia (11.2 mg/dL11.2 \text{ mg/dL}) with an inappropriately elevated PTH (78 pg/mL78 \text{ pg/mL}).
This identifies the hypercalcemia as PTH-dependent, narrowing the differential to primary hyperparathyroidism, familial hypocalciuric hypercalcemia (FHH), and drug-induced causes.
2
Evaluate the 24-hour urine calcium and the calcium-to-creatinine clearance ratio (CCCR).
The 24-hour urine calcium is low (85 mg85 \text{ mg}) and the CCCR is 0.0060.006 (<0.01< 0.01).
A CCCR <0.01< 0.01 strongly suggests enhanced renal calcium reabsorption, which is characteristic of FHH or thiazide diuretic use, and makes primary hyperparathyroidism (typically CCCR >0.02> 0.02) highly unlikely.
3
Correlate the biochemical findings with the patient's medication list.
The patient is actively taking chlorthalidone, a thiazide diuretic.
Thiazides act on the distal convoluted tubule to decrease calcium excretion, producing an identical laboratory profile to FHH (mild hypercalcemia, high-normal or elevated PTH, and profound hypocalciuria).
4
Determine the most appropriate initial management step.
Discontinue the chlorthalidone and reassess.
The pharmacological confounder must be removed to establish an accurate baseline diagnosis before pursuing expensive genetic testing or invasive surgical evaluations.

Anahtar Kavram

Thiazide-induced hypercalcemia and its mimicry of Familial Hypocalciuric Hypercalcemia (FHH)
Soru 1396Soru →

An evaluation is requested for a 48-year-old male who is admitted to the intensive care unit with a 4-day history of coughing up blood-tinged sputum, progressive dyspnea, and passing dark red urine. Over the past six months, he has been treated three times for therapy-resistant maxillary sinusitis and chronic otitis media. Vital signs show a temperature of 37.6∘C37.6^\circ\text{C} (99.7∘F99.7^\circ\text{F}), blood pressure of 165/95 mm Hg165/95\text{ mm Hg}, heart rate of 110/min110/\text{min}, and respiratory rate of 26/min26/\text{min}. Oxygen saturation is 89%89\% on room air. Physical examination reveals ulceration of the nasal septum and bilateral coarse crackles in the lung fields. Laboratory results are as follows:

TestResultReference Range
Serum creatinine2.8 mg/dL2.8\text{ mg/dL}0.6−1.2 mg/dL0.6-1.2\text{ mg/dL}
TSH1.2 μU/mL1.2\text{ }\mu\text{U/mL}0.5−5.0 μU/mL0.5-5.0\text{ }\mu\text{U/mL}
Free T40.6 ng/dL0.6\text{ ng/dL}0.9−1.7 ng/dL0.9-1.7\text{ ng/dL}
Arterial pH7.247.247.35−7.457.35-7.45
pCO2\text{pCO}_224 mm Hg24\text{ mm Hg}35−45 mm Hg35-45\text{ mm Hg}
HCO3−\text{HCO}_3^-10 mEq/L10\text{ mEq/L}22−28 mEq/L22-28\text{ mEq/L}

Urinalysis demonstrates 3+3+ blood, 1+1+ protein, 30−4030-40 dysmorphic red blood cells per high-power field, and occasional red blood cell casts. Chest radiography reveals diffuse bilateral alveolar opacities.

Which of the following is the most appropriate next step in the management of this patient?

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Cevap: Begin therapy with systemic glucocorticoids and rituximab

Cevap

Begin therapy with systemic glucocorticoids and rituximab
The correct next step is to begin therapy with systemic glucocorticoids and rituximab. This patient presents with the classic triad of Granulomatosis with polyangiitis (GPA): upper respiratory tract involvement (chronic sinusitis, otitis media, nasal septal ulceration), lower respiratory tract involvement (hemoptysis from diffuse alveolar hemorrhage), and renal involvement (rapidly progressive glomerulonephritis evidenced by acute kidney injury with dysmorphic RBCs and RBC casts). The simultaneous presence of acute alveolar hemorrhage and rapidly declining renal function is a life-threatening presentation known as pulmonary-renal syndrome. Immediate induction therapy with high-dose systemic glucocorticoids combined with an immunosuppressant (either rituximab or cyclophosphamide) is strictly required to halt progressive multi-organ destruction and preserve organ function.

Adım Adım Çözüm

1
Identify the primary triad of symptoms in the clinical vignette.
The patient has upper respiratory tract disease (chronic sinusitis, nasal septal ulceration), lower respiratory tract disease (hemoptysis, bilateral alveolar opacities), and renal disease (acute kidney injury with dysmorphic RBCs and RBC casts).
Recognizing this classic triad establishes the clinical diagnosis of Granulomatosis with polyangiitis (GPA), an ANCA-associated vasculitis.
2
Evaluate the severity of the patient's presentation.
The patient has diffuse alveolar hemorrhage causing hypoxemia and rapidly progressive glomerulonephritis.
This constellation is known as pulmonary-renal syndrome, which is a life-threatening medical emergency requiring immediate, aggressive intervention.
3
Select the appropriate pharmacological management based on the diagnosis and severity.
Induction therapy with high-dose systemic glucocorticoids combined with either rituximab or cyclophosphamide is chosen.
Aggressive immunosuppression is the standard of care to halt autoimmune tissue destruction, prevent irreversible renal failure, and resolve alveolar hemorrhage in severe GPA.
4
Rule out competing distractors by analyzing the remaining laboratory data.
The acid-base status represents a pure, appropriately compensated metabolic acidosis via Winter's formula (1.5×10+8=23±21.5 \times 10 + 8 = 23 \pm 2). The thyroid panel indicates euthyroid sick syndrome (low T4, normal TSH in critical illness).
Proper data interpretation confirms that sodium bicarbonate and levothyroxine are unindicated and incorrect management steps.

Anahtar Kavram

Patients with Granulomatosis with polyangiitis (GPA) presenting with life-threatening pulmonary-renal syndrome require emergent induction immunosuppressive therapy with high-dose systemic glucocorticoids and rituximab or cyclophosphamide.
Soru 1397Soru →

A 6262-year-old man is hospitalized for the treatment of an acute right-sided pulmonary embolism. He is initially started on a continuous intravenous unfractionated heparin infusion. On hospital day 6, his platelet count is noted to have decreased from a baseline of 240,000/mm3240,000/mm^3 on admission to 90,000/mm390,000/mm^3. Concurrently, he reports new-onset left leg pain and swelling. Venous duplex ultrasonography reveals a new acute deep venous thrombosis in the left femoral vein. Heparin-induced thrombocytopenia is suspected. The heparin infusion is immediately discontinued, and intravenous argatroban is initiated. A serotonin release assay later returns positive, confirming the diagnosis. Four days later, the patient's leg swelling has significantly improved, and his respiratory status remains stable. His current platelet count is 115,000/mm3115,000/mm^3. The patient is eager to transition to an oral anticoagulant and be discharged. Which of the following is the most appropriate next step in the management of this patient's anticoagulation?

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Cevap: Delay the initiation of warfarin until the platelet count recovers to at least 150,000/mm3150,000/mm^3

Cevap

Delay the initiation of warfarin until the platelet count recovers to at least 150,000/mm³.
The correct approach is to delay the initiation of warfarin until the patient's platelet count has recovered to at least 150,000/mm3150,000/mm^3. Heparin-induced thrombocytopenia (HIT) is a highly prothrombotic state caused by IgG autoantibodies against platelet factor 4 (PF4) complexed with heparin. These antibodies activate platelets, leading to consumptive thrombocytopenia and paradoxical thrombosis. When transitioning a patient with HIT to long-term oral anticoagulation with warfarin, timing is critical. Warfarin exerts its effect by inhibiting the vitamin K-dependent synthesis of procoagulant factors (II, VII, IX, and X) as well as the endogenous anticoagulant proteins C and S. Because protein C has a significantly shorter half-life (approximately 8 hours) than most procoagulant factors (e.g., factor II has a half-life of 60 hours), the initiation of warfarin creates a transient hypercoagulable window. If warfarin is started during the acute phase of HIT (while platelets are still low and the thrombotic drive is highest), this rapid depletion of protein C can lead to catastrophic microvascular thrombosis, classically presenting as venous limb gangrene or warfarin-induced skin necrosis. Therefore, a non-heparin parenteral anticoagulant (such as argatroban) must be continued alone until the acute phase has resolved, indicated by a platelet count recovery to ≥150,000/mm3\geq 150,000/mm^3. At that point, warfarin can be initiated with a minimum 5-day overlap with the parenteral agent until the INR is therapeutic.

Adım Adım Çözüm

1
Identify the patient's current clinical status.
The patient has confirmed heparin-induced thrombocytopenia (HIT) complicated by a new deep venous thrombosis, currently treated with argatroban. His platelet count is recovering but is still low at 115,000/mm3115,000/mm^3.
Establishing the current phase of HIT (acute vs. recovering) is necessary to guide the transition to long-term oral anticoagulation.
2
Determine the safety of initiating warfarin in the acute phase of HIT.
Warfarin cannot be safely initiated while the patient is still thrombocytopenic (platelets < 150,000/mm3150,000/mm^3).
Warfarin causes rapid depletion of the anticoagulant protein C before it depletes procoagulant factors. In the already highly prothrombotic state of HIT, this can precipitate venous limb gangrene.
3
Select the appropriate next step in management.
The initiation of warfarin must be delayed until the platelet count reaches at least 150,000/mm3150,000/mm^3.
Waiting for platelet recovery ensures the acute prothrombotic phase of HIT has resolved sufficiently to safely tolerate the transient protein C depletion caused by warfarin.

Anahtar Kavram

In patients with heparin-induced thrombocytopenia, warfarin initiation must be delayed until the platelet count recovers to at least 150,000/mm³ to prevent venous limb gangrene.
Soru 1398Soru →

A 3434-year-old woman presents to the clinic for evaluation of a skin rash. She noticed the rash on her right posterior thigh 44 days ago, and it has steadily increased in size. She recently returned from a camping trip in Maine. The patient reports mild fatigue and muscle aches but denies fever, joint swelling, or shortness of breath. Her temperature is 37.1∘C37.1^\circ\text{C} (98.8∘F98.8^\circ\text{F}), blood pressure is 120/78 mm Hg120/78\text{ mm Hg}, and pulse is 76/min76\text{/min}. Physical examination reveals a 10-cm10\text{-cm}, annular, erythematous plaque with a central area of clearing on the right posterior thigh. The remainder of the examination is unremarkable. Which of the following is the most appropriate next step in management?

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Cevap: Prescribe oral doxycycline

Cevap

Prescribe oral doxycycline
The correct action is to prescribe oral doxycycline. This patient presents with a classic erythema migrans rash (annular, erythematous plaque with central clearing) and a history of recent travel to a Lyme-endemic area, which is diagnostic for early localized Lyme disease. In early localized disease, empiric treatment with an oral antibiotic (such as doxycycline, amoxicillin, or cefuroxime) should be initiated immediately based entirely on clinical findings.

Adım Adım Çözüm

1
Identify the primary clinical finding and its significance.
The patient has a large, expanding annular erythematous plaque with central clearing (erythema migrans) after visiting a Lyme-endemic area.
Erythema migrans is the hallmark physical finding of early localized Lyme disease.
2
Determine the appropriate diagnostic approach.
Diagnosis is made clinically based on the characteristic rash; serologic testing is unnecessary at this stage.
Antibodies to Borrelia burgdorferi often take weeks to develop, so serology has low sensitivity early in the disease course and can yield false-negative results.
3
Select the optimal management strategy.
Initiate empiric oral antibiotic therapy.
Oral doxycycline is the first-line treatment for early localized Lyme disease in non-pregnant adults.

Anahtar Kavram

Diagnosis and management of early localized Lyme disease
Soru 1399Soru →

An occupational health clinic evaluates a 3131-year-old hospital pharmacist for a two-month history of irritability, frequent palpitations, and heat intolerance. She reports poor sleep and an unintentional 4-kg4\text{-kg} (8.8-lb8.8\text{-lb}) weight loss during this period. The patient has no significant past medical history and takes no prescribed medications, although she admits to taking various over-the-counter "energy supplements" to help with long shifts. Her vital signs show a pulse of 112/min112\text{/min} and a blood pressure of 138/82 mm Hg138/82\text{ mm Hg}. Physical examination reveals a fine tremor of the outstretched hands and hyperactive deep tendon reflexes. The eyes show no proptosis, lid lag, or periorbital edema. The thyroid gland is not palpable, and there is no cervical lymphadenopathy or anterior neck tenderness.

Laboratory evaluation shows:
Thyroid-stimulating hormone (TSH): <0.01 μU/mL<0.01\text{ }\mu\text{U/mL} (normal: 0.40.4-4.0 μU/mL4.0\text{ }\mu\text{U/mL})
Free T4: 2.9 ng/dL2.9\text{ ng/dL} (normal: 0.80.8-1.8 ng/dL1.8\text{ ng/dL})
Free T3: 6.2 pg/mL6.2\text{ pg/mL} (normal: 2.32.3-4.2 pg/mL4.2\text{ pg/mL})

A subsequent 2424-hour radioactive iodine uptake scan reveals <1%<1\% uptake (normal: 10%10\%-30%30\%).

Which of the following is the most appropriate next step in the diagnostic workup?

Cevabı ve açıklamayı göster

Cevap: Measurement of serum thyroglobulin

Cevap

Measurement of serum thyroglobulin
This patient presents with clinical and biochemical evidence of primary thyrotoxicosis, confirmed by a suppressed TSH and elevated free T4 and free T3. The subsequent low radioactive iodine uptake (RAIU) indicates that her thyroid gland is not actively synthesizing new hormone. The differential diagnosis for thyrotoxicosis with a low RAIU includes destructive thyroiditis (such as painless or subacute thyroiditis), exogenous thyroid hormone intake (factitious thyrotoxicosis), and ectopic thyroid hormone production (such as struma ovarii). The complete lack of neck pain or tenderness effectively rules out subacute granulomatous thyroiditis. To definitively differentiate between painless thyroiditis (endogenous release of preformed hormone due to follicular destruction) and factitious thyrotoxicosis (exogenous hormone consumption), a serum thyroglobulin level is required. Thyroglobulin is a precursor protein that is co-released into the circulation along with endogenous thyroid hormones. Therefore, thyroglobulin levels will be elevated in destructive thyroiditis but suppressed in exogenous thyroid hormone abuse. Given the patient's profession as a pharmacist, providing access to medications, and her use of unnamed 'energy supplements', factitious thyrotoxicosis is highly suspected.

Adım Adım Çözüm

1
Interpret the initial thyroid function tests.
The patient has a suppressed TSH with elevated free T4 and free T3, confirming primary thyrotoxicosis.
Establishing the biochemical presence of primary thyrotoxicosis is the necessary first step before determining the underlying etiology.
2
Analyze the results of the radioactive iodine uptake (RAIU) scan.
The RAIU is <1%, indicating that the thyroid gland is not actively synthesizing new hormone.
A low RAIU differentiates thyrotoxicosis due to active endogenous overproduction (such as Graves disease or toxic adenoma) from conditions involving preformed hormone release or exogenous hormone intake.
3
Synthesize the clinical presentation with the low RAIU to narrow the differential diagnosis.
The absence of a tender goiter makes subacute (de Quervain) thyroiditis highly unlikely. The primary remaining differentials are painless (silent) thyroiditis and factitious thyrotoxicosis.
Clinical examination features (e.g., presence or absence of pain) help to quickly exclude inflammatory causes of a low RAIU.
4
Select the appropriate confirmatory test to distinguish exogenous from endogenous thyrotoxicosis.
Serum thyroglobulin should be measured.
Thyroglobulin is co-secreted with endogenous thyroid hormone. It is elevated in destructive thyroiditis but profoundly suppressed in factitious thyrotoxicosis due to the exogenous source of hormone suppressing normal glandular activity.

Anahtar Kavram

Patients presenting with thyrotoxicosis and a low radioactive iodine uptake (RAIU) should be evaluated with a serum thyroglobulin level to definitively differentiate between endogenous destructive thyroiditis (which features high thyroglobulin) and exogenous factitious thyrotoxicosis (which features low thyroglobulin).
Soru 1400Soru →

During morning rounds in the intensive care unit, the medical team evaluates a patient with septic shock secondary to a perforated viscus. The patient's arterial blood gas and basic metabolic panel are drawn to assess his acid-base status. The laboratory results reveal a severe primary metabolic acidosis with a serum bicarbonate level of 14 mEq/L14 \text{ mEq/L} and a significantly elevated serum lactate. To determine if a superimposed respiratory acid-base disorder is present, the physician calculates the expected respiratory response. Assuming appropriate respiratory compensation, which of the following is the expected partial pressure of carbon dioxide (PaCO2PaCO_2) in this patient?

Cevabı ve açıklamayı göster

Cevap: 29 mm Hg29 \text{ mm Hg}

Cevap

The expected PaCO2PaCO_2 is 29 mm Hg29 \text{ mm Hg} (with a normal physiological range of ±2\pm 2), calculated using Winter's formula.
The correct expected value is 29 mm Hg29 \text{ mm Hg}. In primary metabolic acidosis, peripheral chemoreceptors sense the low pH and stimulate the respiratory center to increase ventilation. This compensatory hyperventilation blows off CO2CO_2 in an attempt to normalize the pH. The expected PaCO2PaCO_2 can be reliably calculated using Winter's formula: Expected PaCO2=(1.5×[HCO3−])+8±2PaCO_2 = (1.5 \times [HCO_3^-]) + 8 \pm 2. For a bicarbonate of 14 mEq/L14 \text{ mEq/L}, the calculation is (1.5×14)+8=21+8=29(1.5 \times 14) + 8 = 21 + 8 = 29. The expected PaCO2PaCO_2 target is therefore 29 mm Hg29 \text{ mm Hg} (range 2727 to 31 mm Hg31 \text{ mm Hg}). If the measured PaCO2PaCO_2 falls outside this range, a superimposed respiratory disorder is present.

Adım Adım Çözüm

1
Identify the primary acid-base disturbance.
Primary metabolic acidosis.
The patient has a low serum bicarbonate level (14 mEq/L14 \text{ mEq/L}) driven by elevated lactate from septic shock.
2
Select the appropriate formula to calculate respiratory compensation.
Winter's formula: Expected PaCO2=(1.5×[HCO3−])+8±2PaCO_2 = (1.5 \times [HCO_3^-]) + 8 \pm 2.
This formula is specifically validated to determine the expected degree of hyperventilation (and resulting PaCO2PaCO_2) in primary metabolic acidosis.
3
Calculate the expected value.
1.5×14+8=21+8=29 mm Hg1.5 \times 14 + 8 = 21 + 8 = 29 \text{ mm Hg}.
Plugging the patient's bicarbonate level into the formula yields the exact target central value.

Anahtar Kavram

Winter's formula (1.5×[HCO3−]+8±21.5 \times [HCO_3^-] + 8 \pm 2) is used to calculate the expected respiratory compensation (expected PaCO2PaCO_2) in a patient with a primary metabolic acidosis.
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Internal Medicine Alıştırma Soruları — USMLE Step 2 CK — Sayfa 70 | Examkin