Internal Medicine

A 38-year-old mechanic presents to the urgent care clinic complaining of severe flank pain, nausea, and blurry vision that started earlier this morning. He admits to accidentally ingesting a few mouthfuls of a liquid from an unmarked container in his garage while working late last night. His temperature is 36.8°C (98.2°F), blood pressure is 142/88 mm Hg, pulse is 98/min, and respiratory rate is 22/min. Cardiopulmonary examination is unremarkable. Initial laboratory tests reveal the following:

* Serum sodium: $138 \text{ mEq/L}$
* Serum potassium: $4.5 \text{ mEq/L}$
* Serum chloride: $104 \text{ mEq/L}$
* Serum bicarbonate: $14 \text{ mEq/L}$
* Blood urea nitrogen (BUN): $28 \text{ mg/dL}$
* Serum glucose: $126 \text{ mg/dL}$
* Measured serum osmolality: $315 \text{ mOsm/kg H}_2\text{O}$

Based on these findings, what is the patient's calculated serum osmolar gap?

A 74-year-old man is admitted to the hospital with a 3-day history of progressively worsening shortness of breath, orthopnea, and lower extremity swelling. Physical examination reveals elevated jugular venous pressure, bilateral crackles at the lung bases, and 2+ pitting edema. Arterial blood gas on room air shows a pH of 7.48, PaCO $_2$ of 28 mm Hg, and HCO $_3^-$ of 20 mEq/L. The patient is started on intravenous furosemide. A routine admission laboratory panel is drawn, including thyroid function tests, which reveal the following:

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

A $58$-year-old male presents to the outpatient clinic reporting a $5$-month history of profound fatigue, anorexia, a $4$-kg ($8.8$-lb) weight loss, and loss of libido. He also notes mild shortness of breath when climbing stairs and trace swelling in his ankles. Vital signs are temperature $36.6$°C ($97.9$°F), blood pressure $95/60$ mm Hg, pulse $54$/min, and respirations $16$/min. Pulse oximetry is $96\%$ on room air. Physical examination reveals pale skin with no visible hyperpigmentation. Genitourinary examination shows soft, atrophic testes. Neurologic examination demonstrates a delayed relaxation phase of the Achilles tendon reflexes. Trace bilateral pitting edema is present. Lungs are clear to auscultation.

Laboratory evaluation reveals:

Arterial blood gas (room air):
pH: $7.33$
PaCO $_2$: $31$ mm Hg
PaO $_2$: $88$ mm Hg

Urinalysis shows $8$ WBCs/hpf, trace leukocyte esterase, negative nitrites, and no bacteria.

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

A $24$-year-old man is brought to the emergency department by his roommate after being found distressed and complaining of a 'loud ringing' in his ears. The patient has been experiencing nausea and vomited once prior to arrival. The roommate reports finding several empty bottles of over-the-counter pain relievers in their shared bathroom. His temperature is $37.9^\circ\text{C}$ ($100.2^\circ\text{F}$), blood pressure is $118/76$ mm Hg, pulse is $112$/min, and respiratory rate is $28$/min. Physical examination reveals a diaphoretic and anxious patient with deep, rapid respirations.

Based on the laboratory findings, which of the following best describes this patient's acid-base status?

A 74-year-old woman arrives at the emergency department accompanied by her daughter. She complains of rapidly worsening shortness of breath and a cough producing pink, frothy sputum over the past 12 hours. She has a medical history significant for essential hypertension, diet-controlled type 2 diabetes mellitus, and a 45-pack-year smoking history. Her current daily medications are amlodipine and metformin.

Vital signs are as follows:
- Temperature: $37.0^\circ\text{C}$ ($98.6^\circ\text{F}$)
- Blood pressure: $210/115 \text{ mmHg}$
- Pulse: $118/\text{min}$
- Respiratory rate: $30/\text{min}$
- Oxygen saturation: $84\%$ on room air

Physical examination reveals a somnolent patient in severe respiratory distress, using accessory muscles of respiration. Jugular venous distention is prominent when the patient is seated upright. Lung auscultation reveals diffuse expiratory wheezes and coarse crackles extending from the bases to the mid-lung fields bilaterally. Cardiac auscultation demonstrates tachycardia, a regular rhythm, and a loud third heart sound (S3). Bilateral 2+ pitting edema is noted in the lower extremities.

Laboratory and arterial blood gas studies on room air reveal the following:
- Leukocyte count: $8,200/\text{mm}^3$
- Serum creatinine: $1.3 \text{ mg/dL}$
- Thyroid-stimulating hormone (TSH): $1.2 \,\mu\text{U/mL}$ (Normal: $0.5 - 5.0 \,\mu\text{U/mL}$)
- Free T4: $0.7 \text{ ng/dL}$ (Normal: $0.9 - 1.7 \text{ ng/dL}$)
- pH: $7.22$
- PaCO $_2$: $70 \text{ mmHg}$
- PaO $_2$: $50 \text{ mmHg}$
- HCO $_3^-$: $27 \text{ mEq/L}$

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

A first-year internal medicine resident sustains a deep, bleeding needlestick injury to their index finger while drawing arterial blood from a patient with known, poorly controlled HIV infection. Arrange the following steps in the most appropriate chronological sequence for managing this occupational exposure.

Match each patient's clinical presentation and cerebrospinal fluid (CSF) analysis findings with the most appropriate targeted or empiric treatment regimen.

An oncologist is called to the emergency department to evaluate a $62$-year-old male patient who has developed profound lethargy, severe nausea, and diffuse myalgias over the past $5$ days. The patient was diagnosed with metastatic non-small cell lung cancer six months ago and is currently receiving combination immunotherapy with nivolumab and ipilimumab.

Vital signs are as follows: temperature is $37.6^\circ\text{C}$ ($99.7^\circ\text{F}$), blood pressure is $82/50\text{ mmHg}$, heart rate is $115/\text{min}$, and respiratory rate is $18/\text{min}$. Physical examination shows dry mucous membranes, clear lungs to auscultation, and no cutaneous hyperpigmentation.

Laboratory evaluation reveals:
$\text{Sodium}$: $129\text{ mEq/L}$
$\text{Potassium}$: $4.1\text{ mEq/L}$
$\text{Glucose}$: $58\text{ mg/dL}$
$\text{Eosinophils}$: $8\%$
$\text{Thyroid-stimulating hormone (TSH)}$: $0.1\text{ \mu U/mL}$ (Normal: $0.5-5.0\text{ \mu U/mL}$)
$\text{Free T4}$: $0.4\text{ ng/dL}$ (Normal: $0.9-1.7\text{ ng/dL}$)

An $8\text{ AM}$ serum cortisol level has been drawn and is pending.

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

A 45-year-old female patient with newly diagnosed acute myeloid leukemia is currently undergoing induction chemotherapy in the oncology unit. On the tenth day of her treatment course, her body temperature spikes to 38.6°C (101.5°F). Vital signs show a blood pressure of 105/65 mm Hg, a heart rate of 110/min, and respirations of 18/min. She has a tunneled central venous catheter in place. Physical examination reveals no focal signs of infection; her lungs are clear to auscultation, and the catheter site exhibits no erythema or purulent discharge. Laboratory evaluation is notable for a leukocyte count of 400/mm³ with 10% neutrophils, resulting in an absolute neutrophil count of 40/mm³. A diagnosis of high-risk neutropenic fever is established.

Arrange the following clinical steps in the correct chronological sequence for the standard evaluation and management of this patient's condition.

Emergency medical responders bring a $53$-year-old male to the emergency department due to severe, acute-onset respiratory distress. The patient's spouse reports he has been unable to sleep lying flat for the past two nights and has been coughing frequently. His medical history is significant for poorly controlled hypertension, type $2$ diabetes mellitus, and a $30$-pack-year smoking history. On arrival, he is sitting on the edge of the stretcher, diaphoretic, and using accessory muscles to breathe. Vital signs include a temperature of $37.1^\circ\text{C}$ ($98.8^\circ\text{F}$), blood pressure of $192/108\text{ mmHg}$, heart rate of $118/\text{min}$, and respiratory rate of $30/\text{min}$. Pulse oximetry shows an oxygen saturation of $84\%$ on room air. Physical examination reveals prominent jugular venous distention measuring $10\text{ cm H}_2\text{O}$ above the sternal angle. Auscultation of the lungs reveals diffuse expiratory wheezes and scattered crackles in the lower two-thirds of both lung fields. A bedside electrocardiogram demonstrates sinus tachycardia with left ventricular hypertrophy but no acute ST-segment changes. Which of the following is the most appropriate initial step in management?

A $19$-year-old male college student presents to the emergency department accompanied by his roommate after developing a severe headache, confusion, and high fever over the previous $12$ hours. His temperature is $39.6^\circ\text{C}$ ($103.3^\circ\text{F}$), blood pressure is $108/68\text{ mmHg}$, and heart rate is $118\text{ beats/min}$. Physical examination reveals marked nuchal rigidity and a non-blanching petechial rash on his lower extremities. A lumbar puncture is performed, and empiric therapy with intravenous ceftriaxone, vancomycin, and dexamethasone is promptly initiated. Cerebrospinal fluid (CSF) analysis shows a leukocyte count of $3,200\text{ cells/mm}^3$ ($92\%$ neutrophils), a glucose level of $22\text{ mg/dL}$, and a protein level of $165\text{ mg/dL}$. The following day, the patient's mental status improves. CSF culture grows *Neisseria meningitidis*. Antimicrobial susceptibility testing is pending. Which of the following is the most appropriate next step in this patient's antimicrobial management?

A 42-year-old woman presents to her primary care physician reporting progressively worsening fatigue and cold intolerance over the past six months. She also notes that her menstrual periods, which were previously regular, ceased entirely eight months ago. Over the last several weeks, she has been experiencing intermittent, dull headaches. She takes no medications and has no significant past medical history.

Physical examination reveals a blood pressure of $110/70$ mmHg and a pulse of $56$/min. The thyroid gland is not palpable. Neurologic examination demonstrates delayed relaxation of the deep tendon reflexes. Confrontational visual field testing reveals a loss of peripheral vision in both temporal fields.

Laboratory studies show the following:

Which of the following is the most likely underlying mechanism for this patient's clinical and laboratory findings?

A 65-year-old man presents to the outpatient clinic with a 4-day history of a productive cough, fevers, and progressively worsening shortness of breath. His medical history is significant for hypertension and type 2 diabetes mellitus, for which he takes lisinopril and metformin. His temperature is 38.4°C (101.1°F), blood pressure is 132/82 mm Hg, pulse is 98/min, and respiratory rate is 22/min. Pulse oximetry shows an oxygen saturation of 94% on room air. Physical examination reveals bronchial breath sounds and crackles in the right lower lung field. A chest radiograph demonstrates a dense consolidation in the right lower lobe. The physician determines the patient is stable for outpatient management. Which of the following is the most appropriate empiric pharmacotherapy for this patient?

A $54$-year-old man is hospitalized for the initiation of induction chemotherapy for a newly diagnosed high-grade non-Hodgkin lymphoma. Forty-eight hours after starting his chemotherapy regimen, he develops progressive lethargy, generalized muscle cramps, and two episodes of vomiting. His temperature is $37.2^\circ\text{C}$, blood pressure is $105/65\text{ mmHg}$, heart rate is $112\text{/min}$, and respiratory rate is $22\text{/min}$.

Laboratory studies reveal the following:

An arterial blood gas analysis reveals a pH of $7.28$, $\text{pCO}_2$ of $30\text{ mmHg}$, and $\text{HCO}_3^-$ of $14\text{ mEq/L}$. An electrocardiogram demonstrates peaked T waves and a prolonged PR interval. Which of the following is the most appropriate next step in the management of this patient?

A 34-year-old woman presents to the clinic with a 2-day history of pinpoint red rashes on her lower extremities and bleeding from her gums when brushing her teeth. She reports having a mild upper respiratory infection two weeks ago but is otherwise healthy. She takes no medications and has no personal or family history of bleeding disorders. Vital signs are within normal limits. Physical examination reveals diffuse petechiae over the bilateral shins and ankles. There is no palpable hepatosplenomegaly, and no lymphadenopathy is appreciated. Neurologic examination is unremarkable.

Laboratory results are as follows:
Hemoglobin: $12.5 \text{ g/dL}$
Leukocyte count: $7,500/\text{mm}^3$
Platelet count: $14,000/\text{mm}^3$
Prothrombin time: $11 \text{ seconds}$
Activated partial thromboplastin time: $28 \text{ seconds}$
Creatinine: $0.8 \text{ mg/dL}$

A peripheral blood smear shows enlarged platelets but no schistocytes or blasts. What is the most appropriate next step in management?

A 68-year-old man with a history of severe chronic obstructive pulmonary disease (COPD) is admitted to the intensive care unit for acute hypercapnic respiratory failure and suspected community-acquired pneumonia. Upon arrival, he is hemodynamically stable but exhibits severe respiratory distress. Endotracheal intubation and mechanical ventilation are initiated. Shortly after intubation, his blood pressure drops to 78/45 mmHg and his heart rate increases to 122/min. Pulse oximetry shows 92% on an $FiO_2$ of 0.50. Physical examination reveals diffuse wheezing and right lower lobe crackles. A portable chest radiograph demonstrates hyperinflated lungs, a prominent right descending pulmonary artery, and a right lower lobe consolidation, without pulmonary venous congestion. Sputum Gram stain reveals numerous neutrophils and gram-positive, lancet-shaped diplococci. Bedside echocardiography shows a severely dilated right ventricle, a plethoric inferior vena cava, and systolic flattening of the interventricular septum (D-shaped left ventricle); the left ventricular ejection fraction is 65%. Arterial blood gas analysis on current ventilator settings reveals:

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

An independent $54$-year-old woman is evaluated at a walk-in medical center after experiencing one week of escalating breathlessness. She mentions a newly developed, irritating cough that worsens when she attempts to sleep in her bed, prompting her to sleep propped up in a living room chair. The patient has a known history of essential hypertension and has smoked a pack of cigarettes daily for thirty years. Her vitals indicate a blood pressure of $172/96\text{ mmHg}$, a pulse of $108\text{/min}$, and respirations of $24\text{/min}$. Oxygen saturation reads $92\%$ while breathing ambient air. Physical examination reveals distended neck veins when she is seated upright. Auscultating her back reveals widespread crackles at both lung bases that persist despite directed coughing. Cardiac examination is notable for a rapid rate with a clearly audible $S_3$ gallop. Pressing on the skin of her lower legs leaves noticeable indentations bilaterally. Which of the following is the most appropriate initial pharmacologic intervention to relieve this patient's current respiratory symptoms?

Primary care evaluation is requested for a 52-year-old male reporting four weeks of profound fatigue, night sweats, and unintentional weight loss. The patient underwent an uncomplicated cystoscopy for benign prostatic hyperplasia two months ago. Vital signs include a temperature of 38.2°C (100.8°F), blood pressure of 118/76 mmHg, and a heart rate of 94/min. Physical examination reveals splinter hemorrhages on the bilateral fingernails and a new grade III/VI holosystolic murmur loudest at the cardiac apex. Transesophageal echocardiography demonstrates a 1.4-cm oscillating mass on the anterior leaflet of the mitral valve. Four out of four blood culture bottles grow *Enterococcus faecalis*. Antimicrobial susceptibility testing reveals the following:

Based on the antimicrobial susceptibility results, which of the following is the most appropriate definitive intravenous antibiotic regimen?

During an unscheduled visit to a primary care clinic, a 62-year-old retired teacher reports a 3-day history of progressively worsening shortness of breath and a persistent cough. He notes that his sputum has changed from clear to thick and yellow-green over the past 48 hours. His past medical history is significant for chronic obstructive pulmonary disease (COPD), heart failure with preserved ejection fraction (HFpEF), and Hashimoto thyroiditis. His current medications include inhaled tiotropium, oral metoprolol, and oral levothyroxine.

Vital signs are: temperature $37.9^\circ\text{C}$ ($100.2^\circ\text{F}$), blood pressure $138/86 \text{ mmHg}$, pulse $98/\text{min}$, and respirations $24/\text{min}$. Oxygen saturation is $89\%$ on room air.

Physical examination reveals a patient in mild respiratory distress. Lung auscultation demonstrates a prolonged expiratory phase with diffuse bilateral wheezing. Cardiac auscultation reveals a regular rhythm with normal heart sounds; there is no jugular venous distention and no peripheral edema.

Arterial blood gas analysis on room air reveals:
pH: $7.34$
PaCO $_2$: $54 \text{ mmHg}$
PaO $_2$: $60 \text{ mmHg}$
HCO $_3^-$: $28 \text{ mEq/L}$

Laboratory studies show a leukocyte count of $11,200/\text{mm}^3$, a thyroid-stimulating hormone (TSH) level of $3.5 \text{ \mu U/mL}$ (normal: $0.5-5.0 \text{ \mu U/mL}$), and a free T4 of $1.1 \text{ ng/dL}$ (normal: $0.8-1.8 \text{ ng/dL}$).

A chest radiograph displays hyperinflated lungs with flattened diaphragms, but no focal consolidation or pleural effusion.

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

A $62$-year-old man is evaluated in the emergency department for severe right knee pain that began abruptly during the night. The patient states the pain is so intense that he cannot bear weight or tolerate the bedsheet touching his knee. His past medical history includes hypertension, diet-controlled type 2 diabetes mellitus, and stage 4 chronic kidney disease with a baseline estimated glomerular filtration rate of $22 \text{ mL/min}/1.73 \text{ m}^2$. His current medications are amlodipine and atorvastatin. Vital signs show a temperature of $37.6^\circ\text{C}$ ($99.7^\circ\text{F}$), blood pressure of $145/88 \text{ mm Hg}$, and heart rate of $94/\text{min}$. Physical examination reveals a markedly swollen, erythematous, and exquisitely tender right knee. A joint aspiration is performed. Synovial fluid analysis shows a leukocyte count of $42,000/\text{mm}^3$ with $82\%$ segmented neutrophils. Gram stain of the fluid demonstrates no organisms. Polarized light microscopy reveals the presence of needle-shaped crystals with strong negative birefringence. Which of the following is the most appropriate next step in management?