NBME CBSE REAL EXAM 200 QUESTIONS AND
ANSWERS LATEST 2025 COMPLETE EXAM
(USMLE STEP 1)MEDICAL EXAMINATION
1. A 45-year-old man with a history of alcohol abuse presents with hematemesis. Upper endoscopy
reveals dilated submucosal veins in the distal esophagus. Which of the following best explains the
pathogenesis of this finding?
A) Increased hepatic arterial flow
B) Decreased colloid osmotic pressure
C) Increased hydrostatic pressure in the portal vein
D) Decreased synthesis of clotting factors
E) Rupture of gastric mucosal capillaries
Answer: C) Increased hydrostatic pressure in the portal vein
Rationale: Esophageal varices result from portal hypertension (often due to cirrhosis in this patient).
Increased hydrostatic pressure in the portal system forces blood to seek collateral circulation through
the portosystemic anastomoses (e.g., left gastric vein to esophageal veins).
2. A 23-year-old woman presents with acute onset of shortness of breath and right-sided chest pain.
She is on oral contraceptives. Her heart rate is 110/min, respiratory rate 24/min, and oxygen
saturation 88% on room air. A CT pulmonary angiogram shows a filling defect in the right main
pulmonary artery. Which of the following pathophysiologic mechanisms is most directly responsible
for her hypoxemia?
A) Diffusion limitation
B) Right-to-left shunt
C) Decreased minute ventilation
D) V/Q mismatch
E) Hypoventilation
Answer: D) V/Q mismatch
Rationale: Pulmonary embolism leads to increased alveolar dead space (ventilation without perfusion),
,creating a high V/Q ratio in affected areas. Hypoxemia occurs due to redistribution of blood flow to
poorly ventilated areas (low V/Q), resulting in V/Q mismatch.
3. A 67-year-old man with hypertension presents with fatigue and proximal muscle weakness.
Laboratory results show Na+ 145 mEq/L, K+ 2.8 mEq/L, glucose 150 mg/dL. He is taking
hydrochlorothiazide. Which of the following additional findings is most likely?
A) Metabolic acidosis
B) Metabolic alkalosis
C) Respiratory acidosis
D) Respiratory alkalosis
E) Normal anion gap metabolic acidosis
Answer: B) Metabolic alkalosis
Rationale: Thiazide diuretics cause hypokalemia and contraction metabolic alkalosis due to increased
distal sodium delivery, enhanced aldosterone activity, and loss of hydrogen ions.
4. A 60-year-old man with a 50-pack-year smoking history presents with hemoptysis and weight loss.
Chest x-ray shows a right hilar mass. Bronchoscopy reveals a lesion obstructing the right main
bronchus. Biopsy shows small, round blue cells with scant cytoplasm, nuclear molding, and high
mitotic rate. Which paraneoplastic syndrome is most commonly associated with this tumor?
A) Hypercalcemia
B) Syndrome of inappropriate antidiuretic hormone (SIADH)
C) Hypertrophic osteoarthropathy
D) Acanthosis nigricans
E) Gynecomastia
Answer: B) Syndrome of inappropriate antidiuretic hormone (SIADH)
Rationale: Small cell lung carcinoma (SCLC) is strongly associated with ectopic ADH secretion (SIADH).
Other paraneoplastic syndromes include Lambert-Eaton syndrome (anti-VGCC antibodies) and Cushing
syndrome (ectopic ACTH).
5. A 25-year-old man presents with a sore throat, fever, and malaise. Examination reveals posterior
cervical lymphadenopathy and splenomegaly. A peripheral blood smear shows atypical lymphocytes
with abundant cytoplasm that stain with CD20 and CD8. Which of the following is the most likely
causative agent?
A) Cytomegalovirus
B) Epstein-Barr virus
C) Toxoplasma gondii
, D) HIV
E) Streptococcus pyogenes
Answer: B) Epstein-Barr virus
Rationale: Infectious mononucleosis (EBV) presents with pharyngitis, lymphadenopathy (especially
posterior cervical), splenomegaly, and atypical CD8+ T lymphocytes (which are reactive, not malignant).
The atypical cells are CD20 negative in this context despite the question's misdirection; EBV infects B
cells (CD20+), but the atypical lymphocytes are T cells.
6. A 72-year-old woman is brought to the emergency department after falling at home. She has a
history of atrial fibrillation and takes warfarin. Her INR is 4.5. A head CT shows a large
intraparenchymal hemorrhage in the left frontal lobe. Which of the following best describes the
mechanism of action of the reversal agent that should be administered immediately?
A) Provides vitamin K-dependent clotting factors
B) Directly inhibits factor Xa
C) Irreversibly binds to warfarin
D) Increases antithrombin III activity
E) Promotes platelet aggregation
Answer: A) Provides vitamin K-dependent clotting factors
Rationale: For life-threatening bleeding on warfarin, 4-factor prothrombin complex concentrate (PCC) is
preferred as it rapidly replaces factors II, VII, IX, and X (vitamin K-dependent). Vitamin K (phytonadione)
is given concurrently but takes hours to work.
7. A 30-year-old woman presents with episodic headaches, palpitations, and diaphoresis. Her blood
pressure is 190/110 mmHg. She is found to have a 4 cm mass in the right adrenal gland. Which of the
following laboratory findings would most likely confirm the diagnosis?
A) Elevated serum aldosterone
B) Elevated urinary normetanephrines
C) Elevated serum cortisol
D) Low serum renin
E) Hyperglycemia
Answer: B) Elevated urinary normetanephrines
Rationale: The presentation is classic for pheochromocytoma (paroxysmal hypertension, headache,
diaphoresis, palpitations). Diagnosis is confirmed by elevated plasma-free metanephrines or urinary
fractionated metanephrines (normetanephrine and metanephrine).
ANSWERS LATEST 2025 COMPLETE EXAM
(USMLE STEP 1)MEDICAL EXAMINATION
1. A 45-year-old man with a history of alcohol abuse presents with hematemesis. Upper endoscopy
reveals dilated submucosal veins in the distal esophagus. Which of the following best explains the
pathogenesis of this finding?
A) Increased hepatic arterial flow
B) Decreased colloid osmotic pressure
C) Increased hydrostatic pressure in the portal vein
D) Decreased synthesis of clotting factors
E) Rupture of gastric mucosal capillaries
Answer: C) Increased hydrostatic pressure in the portal vein
Rationale: Esophageal varices result from portal hypertension (often due to cirrhosis in this patient).
Increased hydrostatic pressure in the portal system forces blood to seek collateral circulation through
the portosystemic anastomoses (e.g., left gastric vein to esophageal veins).
2. A 23-year-old woman presents with acute onset of shortness of breath and right-sided chest pain.
She is on oral contraceptives. Her heart rate is 110/min, respiratory rate 24/min, and oxygen
saturation 88% on room air. A CT pulmonary angiogram shows a filling defect in the right main
pulmonary artery. Which of the following pathophysiologic mechanisms is most directly responsible
for her hypoxemia?
A) Diffusion limitation
B) Right-to-left shunt
C) Decreased minute ventilation
D) V/Q mismatch
E) Hypoventilation
Answer: D) V/Q mismatch
Rationale: Pulmonary embolism leads to increased alveolar dead space (ventilation without perfusion),
,creating a high V/Q ratio in affected areas. Hypoxemia occurs due to redistribution of blood flow to
poorly ventilated areas (low V/Q), resulting in V/Q mismatch.
3. A 67-year-old man with hypertension presents with fatigue and proximal muscle weakness.
Laboratory results show Na+ 145 mEq/L, K+ 2.8 mEq/L, glucose 150 mg/dL. He is taking
hydrochlorothiazide. Which of the following additional findings is most likely?
A) Metabolic acidosis
B) Metabolic alkalosis
C) Respiratory acidosis
D) Respiratory alkalosis
E) Normal anion gap metabolic acidosis
Answer: B) Metabolic alkalosis
Rationale: Thiazide diuretics cause hypokalemia and contraction metabolic alkalosis due to increased
distal sodium delivery, enhanced aldosterone activity, and loss of hydrogen ions.
4. A 60-year-old man with a 50-pack-year smoking history presents with hemoptysis and weight loss.
Chest x-ray shows a right hilar mass. Bronchoscopy reveals a lesion obstructing the right main
bronchus. Biopsy shows small, round blue cells with scant cytoplasm, nuclear molding, and high
mitotic rate. Which paraneoplastic syndrome is most commonly associated with this tumor?
A) Hypercalcemia
B) Syndrome of inappropriate antidiuretic hormone (SIADH)
C) Hypertrophic osteoarthropathy
D) Acanthosis nigricans
E) Gynecomastia
Answer: B) Syndrome of inappropriate antidiuretic hormone (SIADH)
Rationale: Small cell lung carcinoma (SCLC) is strongly associated with ectopic ADH secretion (SIADH).
Other paraneoplastic syndromes include Lambert-Eaton syndrome (anti-VGCC antibodies) and Cushing
syndrome (ectopic ACTH).
5. A 25-year-old man presents with a sore throat, fever, and malaise. Examination reveals posterior
cervical lymphadenopathy and splenomegaly. A peripheral blood smear shows atypical lymphocytes
with abundant cytoplasm that stain with CD20 and CD8. Which of the following is the most likely
causative agent?
A) Cytomegalovirus
B) Epstein-Barr virus
C) Toxoplasma gondii
, D) HIV
E) Streptococcus pyogenes
Answer: B) Epstein-Barr virus
Rationale: Infectious mononucleosis (EBV) presents with pharyngitis, lymphadenopathy (especially
posterior cervical), splenomegaly, and atypical CD8+ T lymphocytes (which are reactive, not malignant).
The atypical cells are CD20 negative in this context despite the question's misdirection; EBV infects B
cells (CD20+), but the atypical lymphocytes are T cells.
6. A 72-year-old woman is brought to the emergency department after falling at home. She has a
history of atrial fibrillation and takes warfarin. Her INR is 4.5. A head CT shows a large
intraparenchymal hemorrhage in the left frontal lobe. Which of the following best describes the
mechanism of action of the reversal agent that should be administered immediately?
A) Provides vitamin K-dependent clotting factors
B) Directly inhibits factor Xa
C) Irreversibly binds to warfarin
D) Increases antithrombin III activity
E) Promotes platelet aggregation
Answer: A) Provides vitamin K-dependent clotting factors
Rationale: For life-threatening bleeding on warfarin, 4-factor prothrombin complex concentrate (PCC) is
preferred as it rapidly replaces factors II, VII, IX, and X (vitamin K-dependent). Vitamin K (phytonadione)
is given concurrently but takes hours to work.
7. A 30-year-old woman presents with episodic headaches, palpitations, and diaphoresis. Her blood
pressure is 190/110 mmHg. She is found to have a 4 cm mass in the right adrenal gland. Which of the
following laboratory findings would most likely confirm the diagnosis?
A) Elevated serum aldosterone
B) Elevated urinary normetanephrines
C) Elevated serum cortisol
D) Low serum renin
E) Hyperglycemia
Answer: B) Elevated urinary normetanephrines
Rationale: The presentation is classic for pheochromocytoma (paroxysmal hypertension, headache,
diaphoresis, palpitations). Diagnosis is confirmed by elevated plasma-free metanephrines or urinary
fractionated metanephrines (normetanephrine and metanephrine).
