Internal Medicine

A 28-year-old woman comes to the clinic reporting profound fatigue, generalized weakness, and frequent dizzy spells over the past six months. She gave birth to her first child eight months ago. The delivery was complicated by severe uterine atony that required a massive blood transfusion and uterine artery embolization. She has not resumed menstruation and reports that she was completely unable to produce breast milk postpartum. The patient also notes recent cold intolerance and a 4-kg (8.8-lb) weight loss. Her blood pressure is 86/56 mmHg seated and 74/48 mmHg standing. Her heart rate is 92/min. Physical examination reveals delayed relaxation of deep tendon reflexes and a noticeable loss of pubic and axillary hair. Laboratory studies show:

Sodium: 133 mEq/L
Potassium: 4.2 mEq/L
Thyroid-stimulating hormone (TSH): 1.4 $\mu$ U/mL (Normal: 0.4–4.0 $\mu$ U/mL)
Free thyroxine (T4): 0.5 ng/dL (Normal: 0.9–1.7 ng/dL)

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

A 34-year-old man with advanced, untreated HIV infection is evaluated in the emergency department for a two-week history of constant, severe headaches, low-grade fevers, and intermittent nausea. He appears lethargic. Vital signs show a temperature of 38.1°C (100.6°F), blood pressure of 118/76 mmHg, and a heart rate of 92/min. Neurologic examination shows mild nuchal rigidity but no focal deficits. Laboratory studies confirm a CD4 count of 18 cells/mm³. A lumbar puncture is performed, demonstrating an elevated opening pressure of 290 mm H2O. Cerebrospinal fluid (CSF) analysis reveals 45 leukocytes/mm³ (90% lymphocytes), a glucose level of 32 mg/dL, and a protein level of 88 mg/dL. A CSF India ink stain displays encapsulated budding yeast, and the cryptococcal antigen assay is profoundly positive.

Arrange the following therapeutic interventions in the most appropriate chronological order of their initiation for the optimal management of this patient.

An emergency medical services team arrives at the hospital with an altered, lethargic male patient who was found severely confused at home by his family. The patient is $68$ years old and has a known history of extensive tobacco use ($40$ pack-years). According to his family, he has experienced worsening constipation and fatigue over the last seven days. Vital signs upon arrival include a temperature of $37.2^\circ\text{C}$ ($99.0^\circ\text{F}$), a blood pressure of $98/58\text{ mm Hg}$, and a heart rate of $112/\text{min}$. Clinical evaluation demonstrates pronounced signs of volume depletion, including parched oral mucosa and delayed capillary refill. Urgent serum chemistries reveal a total calcium concentration of $15.6\text{ mg/dL}$, an albumin concentration of $3.8\text{ g/dL}$, and a creatinine of $2.1\text{ mg/dL}$ (previously $0.9\text{ mg/dL}$). An electrocardiogram demonstrates a shortened QT interval.

Arrange the following therapeutic and diagnostic interventions in the most appropriate chronological sequence for managing this patient's acute presentation, from immediate life-saving stabilization to definitive evaluation.

During morning rounds, a $68$-year-old female is evaluated on her third day of hospitalization for community-acquired pneumonia. She initially presented with a fever, productive cough, and worsening shortness of breath. Her medical history includes chronic obstructive pulmonary disease (COPD) and osteoarthritis. On admission, she was started on intravenous levofloxacin and oral prednisone.

Today, she reports feeling much better and is tolerating a regular diet. Her temperature is $37.1^\circ C$ ($98.8^\circ F$), blood pressure is $128/78$ mm Hg, pulse is $82$/min, and respiratory rate is $16$/min. Pulse oximetry shows $94\%$ on room air.

Physical examination reveals a normal jugular venous pressure of $6$ cm $H_2O$. Lung auscultation shows prolonged expiration and scattered end-expiratory wheezes, but the bibasilar crackles heard on admission have resolved. She has trace bilateral pitting edema at the ankles, which is unchanged from her baseline.

Laboratory results from this morning show:
Leukocyte count: $7,500/mm^3$
Thyroid-stimulating hormone (TSH): $0.6$ $\mu U/mL$ (Normal: $0.4-4.0$ $\mu U/mL$)
Free thyroxine (T4): $0.7$ ng/dL (Normal: $0.9-1.7$ ng/dL)

Arterial blood gas (room air):
$pH$: $7.38$
$PaCO_2$: $54$ mm Hg
$PaO_2$: $72$ mm Hg
$HCO_3^-$: $31$ mEq/L

Sputum cultures obtained on admission have grown Streptococcus pneumoniae that is susceptible to penicillin, amoxicillin, ceftriaxone, levofloxacin, and vancomycin.

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

A 32-year-old woman is brought to the emergency department by her husband due to progressive lethargy, profound fatigue, and confusion over the past 24 hours. She gave birth to her second child 6 weeks ago; the delivery was complicated by uterine atony and severe postpartum hemorrhage requiring massive blood transfusions. Since discharge, she has been unable to breastfeed and has not resumed menstruation. Her husband mentions she has been very withdrawn and tearful, and he is concerned she might have bipolar disorder like her mother. On physical examination, the patient is somnolent. Temperature is 36.1°C (97.0°F), blood pressure is 82/50 mmHg, and pulse is 112/min. Capillary refill is 4 seconds. Laboratory studies show:

Sodium: 129 mEq/L
Potassium: 4.2 mEq/L
Thyroid-stimulating hormone (TSH): 1.2 µU/mL (Normal: 0.4–4.0 µU/mL)
Free thyroxine (T4): 0.4 ng/dL (Normal: 0.9–1.7 ng/dL)

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

A 71-year-old man with a history of a cerebrovascular accident and neurogenic bladder managed with a chronic indwelling urethral catheter is evaluated during a routine home health visit. He reports feeling well and denies fever, chills, flank pain, suprapubic discomfort, or increased spasticity. His temperature is $37.0^\circ\text{C}$ ($98.6^\circ\text{F}$), blood pressure is $130/80\text{ mmHg}$, heart rate is $76/\text{min}$, and respiratory rate is $14/\text{min}$. Physical examination reveals a soft, non-tender abdomen and no costovertebral angle tenderness. The urine in his collection bag appears cloudy. A urinalysis reveals positive leukocyte esterase and $30$ white blood cells per high-power field. A urine culture obtained 48 hours ago grows $>100,000\text{ CFU/mL}$ of *Pseudomonas aeruginosa*. Which of the following is the most appropriate next step in management?

A clinical guideline committee is creating a quick-reference protocol for managing specific infectious disease exposures. Match each patient scenario with the single most appropriate pharmacological management plan.

A $42$-year-old woman is admitted to the hospital for profound, progressive generalized muscle weakness and a $6$-kg ($13.2$-lb) weight loss over the past $3$ months. She has recently noticed the new onset of dark, coarse hair on her chin and upper lip. She has a $30$-pack-year smoking history. Vital signs show a blood pressure of $174/102$ mm Hg. Physical examination reveals noticeable temporal wasting, generalized muscle atrophy, and hyperpigmentation along the palmar creases and oral mucosa.

Initial laboratory studies show:
Sodium ($Na^+$): $146$ mEq/L
Potassium ($K^+$): $2.4$ mEq/L
Chloride ($Cl^-$): $96$ mEq/L
Bicarbonate ($HCO_3^-$): $36$ mEq/L
Glucose: $255$ mg/dL
Free $T_4$: $0.6$ ng/dL (Normal: $0.9$-$1.7$ ng/dL)
$TSH$: $0.8$ $\mu$ U/mL (Normal: $0.5$-$5.0$ $\mu$ U/mL)

Which of the following is the most likely additional finding in this patient?

A $52$-year-old man is evaluated in the clinic for persistently elevated blood pressure. He is currently taking maximally tolerated doses of lisinopril, amlodipine, and hydrochlorothiazide. His blood pressure today is $168/94\text{ mmHg}$, and his heart rate is $76\text{/min}$. Laboratory studies reveal a serum potassium level of $3.0\text{ mEq/L}$ and a serum sodium level of $144\text{ mEq/L}$. The patient's antihypertensive regimen is transitioned to non-interfering medications (e.g., verapamil and doxazosin), and his hypokalemia is corrected with oral potassium supplementation. The physician strongly suspects a specific endocrine etiology for his resistant hypertension and hypokalemia. Arrange the following diagnostic steps in the most appropriate chronological sequence to definitively evaluate and manage this patient's suspected condition.

A 71-year-old man is evaluated in the clinic for a 3-month history of worsening lower back pain and generalized fatigue. The pain is deep, achy, and localized to the mid-lumbar region without radiation to the legs. He also reports new-onset constipation and increased frequency of urination. He has no significant past medical history and takes no medications. His temperature is $37.0^\circ\text{C}$ ($98.6^\circ\text{F}$), blood pressure is $142/88$ mmHg, pulse is $84$/min, and respiratory rate is $14$/min. Physical examination shows midline point tenderness over the L4 vertebra. Neurologic examination of the lower extremities shows $5/5$ strength with normal deep tendon reflexes.

Laboratory results are as follows:

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

Review the following clinical presentations and arterial blood gas results. Which primary acid-base disorder best matches each clinical vignette?

A 48-year-old man presents to the clinic reporting progressive enlargement of his hands and feet over the past $4$ years. He recently had to resize his wedding ring and notes that his shoes no longer fit. He also complains of increased sweating, joint pain, and frequent frontal headaches. His wife mentions that his jaw has become more prominent and there are new gaps between his teeth. His blood pressure is $165/95$ mmHg. Arrange the following steps in the most appropriate chronological order for the diagnostic workup and initial definitive management of this patient's suspected condition.

During a routine follow-up, a 28-year-old female patient complains of new-onset fatigue and profound muscle weakness. She has a notable past medical history of recurrent nephrolithiasis. Her vital signs are within normal limits.

Laboratory testing reveals the following values:

To help differentiate the cause of her normal anion gap metabolic acidosis, the attending physician requests calculation of the urine anion gap.

What is this patient's urine anion gap (in mEq/L)?

A $78$-year-old woman is evaluated in the hospital for worsening renal function. She was admitted $4$ days ago for acute decompensated heart failure and has been receiving aggressive intravenous bumetanide therapy. Over the past $24$ hours, her urine output has decreased to $300\text{ mL}$. On physical examination, her blood pressure is $105/65\text{ mmHg}$ and pulse is $92/\text{min}$. Jugular venous pressure is undetectable, and her lungs are clear to auscultation. Laboratory studies are obtained:

Based on the laboratory values, calculate the fractional excretion of urea ($FE_{Urea}$) as a percentage to help determine the etiology of her acute kidney injury.

A triage nurse urgently calls a physician to evaluate an $80$-year-old man who was just brought to the hospital by his son. The son reports that the patient suddenly developed excruciating abdominal pain two hours ago but now appears extremely lethargic and confused. The patient has a history of medication nonadherence for his paroxysmal atrial fibrillation. On physical examination, the abdomen is soft and non-tender to deep palpation. He is tachypneic with deep, rapid respirations.

Initial laboratory studies show:
Serum $\text{Na}^+$: $140 \text{ mEq/L}$
Serum $\text{Cl}^-$: $100 \text{ mEq/L}$
Serum $\text{HCO}_3^-$: $10 \text{ mEq/L}$

Arterial blood gas analysis on room air reveals a pH of $7.22$ and a $\text{pCO}_2$ of $23 \text{ mm Hg}$.

Based on these findings, which of the following is the most accurate description of this patient's acid-base status?

Six months after a complicated vaginal delivery, a $29$-year-old woman presents for evaluation of profound exhaustion and cold intolerance. Her obstetrical history is significant for a severe postpartum hemorrhage that necessitated emergency uterine artery embolization and multiple blood transfusions. Since the delivery, she has experienced persistent amenorrhea and was entirely unable to lactate. Vital signs include a blood pressure of $92/58\ \text{mmHg}$ and a heart rate of $58/\text{min}$. On examination, there is noticeable thinning of the lateral eyebrows, loss of axillary hair, and delayed relaxation of the ankle jerk reflexes. Routine blood work reveals the following:

Based on these findings, which of the following is the most accurate pathophysiologic explanation for this patient's thyroid laboratory abnormalities?

Match each antihyperglycemic medication with its primary mechanism of action.

Match each clinical exposure scenario with the most appropriate definitive post-exposure prophylaxis (PEP) or management regimen based on current clinical guidelines.

A 24-year-old man is brought to the emergency department by paramedics after being found unresponsive in his garage. An open bottle of antifreeze was found nearby. His temperature is $36.5^\circ\text{C}$ ($97.7^\circ\text{F}$), blood pressure is $110/70\text{ mm Hg}$, pulse is $112\text{/min}$, and respirations are $28\text{/min}$ and deep. Physical examination reveals a comatose patient with no focal neurologic deficits.

Laboratory studies show the following:
Serum sodium: $138\text{ mEq/L}$
Serum potassium: $5.0\text{ mEq/L}$
Serum chloride: $104\text{ mEq/L}$
Serum bicarbonate: $10\text{ mEq/L}$
Blood urea nitrogen: $14\text{ mg/dL}$
Serum creatinine: $1.2\text{ mg/dL}$
Serum glucose: $90\text{ mg/dL}$
Measured serum osmolality: $315\text{ mOsm/kg H}_2\text{O}$

Arterial blood gas on room air:
pH: $7.20$
pCO $_2$: $24\text{ mm Hg}$
pO $_2$: $95\text{ mm Hg}$

What is this patient's serum osmolar gap? (Enter the value only)

A $72$-year-old woman is evaluated on hospital day $4$ for worsening renal function. She was admitted for acute decompensated heart failure and has been receiving intravenous furosemide. Over the past $48$ hours, her weight has decreased by $4.5\text{ kg}$, but her urine output has dropped to $300\text{ mL}$ over the last $12$ hours. Her blood pressure is $95/60\text{ mmHg}$ and heart rate is $102\text{/min}$. Laboratory studies show:

What is this patient's fractional excretion of urea ($FE_{Urea}$)? (Express the answer as a percentage).