NBME CBSE & USMLE STEP 1
COMPREHENSIVE MEDICAL
EXAMINATION QUESTIONS AND
ANSWERS
1. A 45-year-old male with a history of chronic epigastric pain and peptic ulcers is found to
have a serum gastrin level of 1200 pg/mL. A secretin stimulation test is performed. Which of
the following results is most characteristic of his condition?
A. Paradoxical increase in serum gastrin levels
B. No change in serum gastrin levels
C. Decrease in serum gastrin levels
D. Inhibition of gastric acid secretion
Answer: A
Conceptual Explanation: In Zollinger-Ellison syndrome (gastrinoma), secretin
paradoxically stimulates gastrin release from tumor cells, whereas it normally inhibits
gastrin release from G cells.
,2. A 4-year-old boy presents with recurrent sinopulmonary infections and is found to have
very low levels of all immunoglobulin classes. Flow cytometry reveals a lack of B cells
(CD19+). Which gene is likely mutated?
A. ADA
B. IL2RG
C. BTK
D. CD40L
Answer: C
Conceptual Explanation: Bruton Agammaglobulinemia is caused by a mutation in the
Bruton Tyrosine Kinase (BTK) gene, leading to a failure of B-cell maturation.
3. What is the primary mechanism of action of Digoxin in the management of congestive
heart failure?
A. Activation of Adenylate Cyclase
B. Inhibition of Phosphodiesterase III
C. Blockade of Beta-1 adrenergic receptors
D. Inhibition of the Na+/K+ ATPase pump
Answer: D
, Conceptual Explanation: Digoxin inhibits the Na+/K+ ATPase, which increases
intracellular sodium, leading to decreased calcium efflux via the Na+/Ca2+ exchanger and
increased contractility.
4. A patient with multiple myeloma presents with bone pain and renal failure. What would
you expect to see on urine electrophoresis?
A. Bence-Jones proteins
B. Albuminuria
C. Hemoglobinuria
D. Myoglobinuria
Answer: A
Conceptual Explanation: Multiple myeloma is associated with the production of
monoclonal light chains, known as Bence-Jones proteins, which are excreted in the urine.
5. A 6-year-old child presents with generalized edema following a viral infection. Urinalysis
shows 4+ protein. Electron microscopy of a renal biopsy reveals effacement of podocyte foot
processes. What is the most likely diagnosis?
A. Membranous Nephropathy
B. Focal Segmental Glomerulosclerosis
C. Minimal Change Disease
D. Post-streptococcal Glomerulonephritis
COMPREHENSIVE MEDICAL
EXAMINATION QUESTIONS AND
ANSWERS
1. A 45-year-old male with a history of chronic epigastric pain and peptic ulcers is found to
have a serum gastrin level of 1200 pg/mL. A secretin stimulation test is performed. Which of
the following results is most characteristic of his condition?
A. Paradoxical increase in serum gastrin levels
B. No change in serum gastrin levels
C. Decrease in serum gastrin levels
D. Inhibition of gastric acid secretion
Answer: A
Conceptual Explanation: In Zollinger-Ellison syndrome (gastrinoma), secretin
paradoxically stimulates gastrin release from tumor cells, whereas it normally inhibits
gastrin release from G cells.
,2. A 4-year-old boy presents with recurrent sinopulmonary infections and is found to have
very low levels of all immunoglobulin classes. Flow cytometry reveals a lack of B cells
(CD19+). Which gene is likely mutated?
A. ADA
B. IL2RG
C. BTK
D. CD40L
Answer: C
Conceptual Explanation: Bruton Agammaglobulinemia is caused by a mutation in the
Bruton Tyrosine Kinase (BTK) gene, leading to a failure of B-cell maturation.
3. What is the primary mechanism of action of Digoxin in the management of congestive
heart failure?
A. Activation of Adenylate Cyclase
B. Inhibition of Phosphodiesterase III
C. Blockade of Beta-1 adrenergic receptors
D. Inhibition of the Na+/K+ ATPase pump
Answer: D
, Conceptual Explanation: Digoxin inhibits the Na+/K+ ATPase, which increases
intracellular sodium, leading to decreased calcium efflux via the Na+/Ca2+ exchanger and
increased contractility.
4. A patient with multiple myeloma presents with bone pain and renal failure. What would
you expect to see on urine electrophoresis?
A. Bence-Jones proteins
B. Albuminuria
C. Hemoglobinuria
D. Myoglobinuria
Answer: A
Conceptual Explanation: Multiple myeloma is associated with the production of
monoclonal light chains, known as Bence-Jones proteins, which are excreted in the urine.
5. A 6-year-old child presents with generalized edema following a viral infection. Urinalysis
shows 4+ protein. Electron microscopy of a renal biopsy reveals effacement of podocyte foot
processes. What is the most likely diagnosis?
A. Membranous Nephropathy
B. Focal Segmental Glomerulosclerosis
C. Minimal Change Disease
D. Post-streptococcal Glomerulonephritis
