Diagnostic Reasoning Comprehensive Practice
Exam 2026 Edition Questions Verified Answers
with Detailed Rationales
1.
A 64-year-old man presents with progressive exertional
dyspnea and fatigue. He has a 40-pack-year smoking history.
Examination reveals a harsh systolic murmur at the right upper
sternal border radiating to the carotids. Echocardiography
shows an aortic valve area of 0.7 cm², mean gradient of 48
mmHg, and left ventricular ejection fraction of 55%. Which
finding most strongly supports severe symptomatic aortic
stenosis as the primary cause of his symptoms?
A. Left ventricular hypertrophy
B. Reduced aortic valve area with elevated transvalvular
gradient
C. Mild mitral regurgitation
D. Increased left atrial volume
Answer: B. Reduced aortic valve area with elevated
transvalvular gradient
,Rationale: An aortic valve area below 1.0 cm² combined with a
mean gradient above 40 mmHg is consistent with severe high-
gradient aortic stenosis. In a symptomatic patient, this provides
strong evidence that the valvular lesion explains the exertional
dyspnea.
2.
A 28-year-old woman develops sudden pleuritic chest pain and
dyspnea three days after returning from a 12-hour
international flight. Her heart rate is 118/min, oxygen
saturation is 91% on room air, and the left calf is mildly swollen.
Which diagnosis is most likely?
A. Acute pericarditis
B. Pulmonary embolism
C. Pneumothorax
D. Viral pleuritis
Answer: B. Pulmonary embolism
Rationale: Prolonged immobility, tachycardia, unilateral leg
swelling, pleuritic chest pain, and hypoxemia strongly suggest
venous thromboembolism with pulmonary embolism. The
clinical presentation should prompt risk stratification and
appropriate diagnostic testing.
,3.
A 72-year-old man presents with confusion, fever, and
hypotension. Laboratory studies show sodium 128 mEq/L,
glucose 96 mg/dL, serum osmolality 270 mOsm/kg, urine
osmolality 650 mOsm/kg, and urine sodium 70 mEq/L. He is
clinically euvolemic. Which diagnosis best explains these
findings?
A. Primary polydipsia
B. SIADH
C. Cerebral salt wasting
D. Diabetes insipidus
Answer: B. SIADH
Rationale: SIADH causes hypotonic hyponatremia with
inappropriately concentrated urine and elevated urine sodium
in a clinically euvolemic patient. The high urine osmolality
indicates persistent antidiuretic hormone activity.
4.
A 45-year-old woman presents with episodic headaches,
palpitations, diaphoresis, and severe hypertension. During an
episode, plasma free metanephrines are markedly elevated. CT
reveals a 4-cm adrenal mass. Which diagnosis is most likely?
, A. Primary hyperaldosteronism
B. Pheochromocytoma
C. Adrenal cortical carcinoma
D. Cushing syndrome
Answer: B. Pheochromocytoma
Rationale: Episodic headache, sweating, palpitations,
hypertension, and elevated plasma metanephrines strongly
indicate catecholamine secretion from a pheochromocytoma.
5.
A 36-year-old man develops jaundice and dark urine after
beginning a new medication. Laboratory studies reveal
markedly elevated AST and ALT with only mild alkaline
phosphatase elevation. Which pattern of liver injury is present?
A. Cholestatic
B. Hepatocellular
C. Infiltrative
D. Posthepatic obstructive
Answer: B. Hepatocellular
Rationale: A disproportionate elevation of aminotransferases
compared with alkaline phosphatase indicates a hepatocellular
Exam 2026 Edition Questions Verified Answers
with Detailed Rationales
1.
A 64-year-old man presents with progressive exertional
dyspnea and fatigue. He has a 40-pack-year smoking history.
Examination reveals a harsh systolic murmur at the right upper
sternal border radiating to the carotids. Echocardiography
shows an aortic valve area of 0.7 cm², mean gradient of 48
mmHg, and left ventricular ejection fraction of 55%. Which
finding most strongly supports severe symptomatic aortic
stenosis as the primary cause of his symptoms?
A. Left ventricular hypertrophy
B. Reduced aortic valve area with elevated transvalvular
gradient
C. Mild mitral regurgitation
D. Increased left atrial volume
Answer: B. Reduced aortic valve area with elevated
transvalvular gradient
,Rationale: An aortic valve area below 1.0 cm² combined with a
mean gradient above 40 mmHg is consistent with severe high-
gradient aortic stenosis. In a symptomatic patient, this provides
strong evidence that the valvular lesion explains the exertional
dyspnea.
2.
A 28-year-old woman develops sudden pleuritic chest pain and
dyspnea three days after returning from a 12-hour
international flight. Her heart rate is 118/min, oxygen
saturation is 91% on room air, and the left calf is mildly swollen.
Which diagnosis is most likely?
A. Acute pericarditis
B. Pulmonary embolism
C. Pneumothorax
D. Viral pleuritis
Answer: B. Pulmonary embolism
Rationale: Prolonged immobility, tachycardia, unilateral leg
swelling, pleuritic chest pain, and hypoxemia strongly suggest
venous thromboembolism with pulmonary embolism. The
clinical presentation should prompt risk stratification and
appropriate diagnostic testing.
,3.
A 72-year-old man presents with confusion, fever, and
hypotension. Laboratory studies show sodium 128 mEq/L,
glucose 96 mg/dL, serum osmolality 270 mOsm/kg, urine
osmolality 650 mOsm/kg, and urine sodium 70 mEq/L. He is
clinically euvolemic. Which diagnosis best explains these
findings?
A. Primary polydipsia
B. SIADH
C. Cerebral salt wasting
D. Diabetes insipidus
Answer: B. SIADH
Rationale: SIADH causes hypotonic hyponatremia with
inappropriately concentrated urine and elevated urine sodium
in a clinically euvolemic patient. The high urine osmolality
indicates persistent antidiuretic hormone activity.
4.
A 45-year-old woman presents with episodic headaches,
palpitations, diaphoresis, and severe hypertension. During an
episode, plasma free metanephrines are markedly elevated. CT
reveals a 4-cm adrenal mass. Which diagnosis is most likely?
, A. Primary hyperaldosteronism
B. Pheochromocytoma
C. Adrenal cortical carcinoma
D. Cushing syndrome
Answer: B. Pheochromocytoma
Rationale: Episodic headache, sweating, palpitations,
hypertension, and elevated plasma metanephrines strongly
indicate catecholamine secretion from a pheochromocytoma.
5.
A 36-year-old man develops jaundice and dark urine after
beginning a new medication. Laboratory studies reveal
markedly elevated AST and ALT with only mild alkaline
phosphatase elevation. Which pattern of liver injury is present?
A. Cholestatic
B. Hepatocellular
C. Infiltrative
D. Posthepatic obstructive
Answer: B. Hepatocellular
Rationale: A disproportionate elevation of aminotransferases
compared with alkaline phosphatase indicates a hepatocellular
