NBME CBSE Real Exam Questions And Correct
Answers With Rationales
NBME CBSE Practice Questions (Set 1)
Question 1
A 65-year-old man presents with chest pain radiating to his left arm. ECG shows ST elevation in leads
II, III, and aVF. Which coronary artery is most likely occluded?
• A. Left anterior descending
• B. Left circumflex
• C. Right coronary artery
• D. Posterior descending
Rationale: ST elevation in II, III, and aVF indicates an inferior wall MI, usually due to right coronary
artery occlusion. LAD affects anterior wall; circumflex affects lateral wall; PDA supplies posterior wall.
Question 2
A patient with chronic alcohol use presents with confusion, ataxia, and ophthalmoplegia. Which
vitamin deficiency is most likely?
• A. Vitamin B1 (Thiamine)
• B. Vitamin B6 (Pyridoxine)
• C. Vitamin B12 (Cobalamin)
• D. Vitamin B3 (Niacin)
Rationale: Classic triad of Wernicke’s encephalopathy is due to thiamine deficiency. Alcohol impairs
absorption and storage. Other B vitamins cause different neurologic or hematologic issues.
Question 3
A newborn has persistent vomiting after feeding and a distended abdomen. Imaging shows a "double
bubble" sign. What is the most likely diagnosis?
• A. Duodenal atresia
• B. Pyloric stenosis
• C. Hirschsprung disease
, • D. Malrotation with volvulus
Rationale: Double bubble sign = stomach + proximal duodenum dilation → duodenal atresia, often
associated with Down syndrome. Pyloric stenosis shows projectile vomiting but no double bubble.
Question 4
Which neurotransmitter is decreased in both Parkinson’s disease and depression?
• A. Dopamine
• B. Serotonin
• C. GABA
• D. Acetylcholine
Rationale: Parkinson’s involves loss of dopaminergic neurons in substantia nigra. Dopamine
deficiency also contributes to depression. Serotonin is decreased in depression but not Parkinson’s.
Question 5
A patient develops hemolytic anemia after taking sulfa drugs. Which enzyme deficiency is most
likely?
• A. Glucose-6-phosphate dehydrogenase (G6PD)
• B. Pyruvate kinase
• C. Hexokinase
• D. Lactate dehydrogenase
Rationale: G6PD deficiency → impaired NADPH production → oxidative stress → hemolysis after
sulfa drugs, fava beans, or infections.
Question 6
A 40-year-old woman presents with heat intolerance, weight loss, and palpitations. Labs show
decreased TSH and elevated free T4. What is the most likely diagnosis?
• A. Hashimoto thyroiditis
• B. Subacute thyroiditis
• C. Graves disease
• D. Toxic multinodular goiter
Rationale: Graves disease = autoimmune stimulation of TSH receptor → ↑T4, ↓TSH. Hashimoto =
hypothyroidism. Subacute thyroiditis = painful thyroid. Toxic multinodular goiter = multiple nodules.
Question 7
Which of the following is a side effect of long-term corticosteroid use?
• A. Hypoglycemia
• B. Osteoporosis
Answers With Rationales
NBME CBSE Practice Questions (Set 1)
Question 1
A 65-year-old man presents with chest pain radiating to his left arm. ECG shows ST elevation in leads
II, III, and aVF. Which coronary artery is most likely occluded?
• A. Left anterior descending
• B. Left circumflex
• C. Right coronary artery
• D. Posterior descending
Rationale: ST elevation in II, III, and aVF indicates an inferior wall MI, usually due to right coronary
artery occlusion. LAD affects anterior wall; circumflex affects lateral wall; PDA supplies posterior wall.
Question 2
A patient with chronic alcohol use presents with confusion, ataxia, and ophthalmoplegia. Which
vitamin deficiency is most likely?
• A. Vitamin B1 (Thiamine)
• B. Vitamin B6 (Pyridoxine)
• C. Vitamin B12 (Cobalamin)
• D. Vitamin B3 (Niacin)
Rationale: Classic triad of Wernicke’s encephalopathy is due to thiamine deficiency. Alcohol impairs
absorption and storage. Other B vitamins cause different neurologic or hematologic issues.
Question 3
A newborn has persistent vomiting after feeding and a distended abdomen. Imaging shows a "double
bubble" sign. What is the most likely diagnosis?
• A. Duodenal atresia
• B. Pyloric stenosis
• C. Hirschsprung disease
, • D. Malrotation with volvulus
Rationale: Double bubble sign = stomach + proximal duodenum dilation → duodenal atresia, often
associated with Down syndrome. Pyloric stenosis shows projectile vomiting but no double bubble.
Question 4
Which neurotransmitter is decreased in both Parkinson’s disease and depression?
• A. Dopamine
• B. Serotonin
• C. GABA
• D. Acetylcholine
Rationale: Parkinson’s involves loss of dopaminergic neurons in substantia nigra. Dopamine
deficiency also contributes to depression. Serotonin is decreased in depression but not Parkinson’s.
Question 5
A patient develops hemolytic anemia after taking sulfa drugs. Which enzyme deficiency is most
likely?
• A. Glucose-6-phosphate dehydrogenase (G6PD)
• B. Pyruvate kinase
• C. Hexokinase
• D. Lactate dehydrogenase
Rationale: G6PD deficiency → impaired NADPH production → oxidative stress → hemolysis after
sulfa drugs, fava beans, or infections.
Question 6
A 40-year-old woman presents with heat intolerance, weight loss, and palpitations. Labs show
decreased TSH and elevated free T4. What is the most likely diagnosis?
• A. Hashimoto thyroiditis
• B. Subacute thyroiditis
• C. Graves disease
• D. Toxic multinodular goiter
Rationale: Graves disease = autoimmune stimulation of TSH receptor → ↑T4, ↓TSH. Hashimoto =
hypothyroidism. Subacute thyroiditis = painful thyroid. Toxic multinodular goiter = multiple nodules.
Question 7
Which of the following is a side effect of long-term corticosteroid use?
• A. Hypoglycemia
• B. Osteoporosis
