NBME CBSE – National Board of Medical
Examiners – 2026/2027 Edition –
Questions and Answers for Medical
Students and International Medical
Graduates
Question 1
A 40-year-old woman at 5 months' gestation comes to the physician for amniocentesis.
Results show a normal 46,XY karyotype of the fetus. Four months later, the newborn is
delivered, and examination shows a female phenotype with mild clitoral enlargement.
Ultrasonography shows the presence of male but not female genital ducts. This
newborn most likely has a mutation of the gene for which of the following factors?
A) Anti-paramesonephric (Müllerian) hormone
B) 5α-Reductase
C) SRY protein
D) Steroid sulfatase
E) Zinc finger transcription factor Wilms tumor 1
Correct Answer: B) 5α-Reductase
Rationale:
5α-reductase is an enzyme that converts testosterone to dihydrotestosterone (DHT).
Testosterone promotes the development of the mesonephric (Wolffian) ducts, which
,develop into the epididymis, vas deferens, and seminal vesicles. DHT, on the other hand,
is essential for the development of male external genitalia and the prostate from the
genital tubercle and urogenital sinus.
Individuals with 5α-reductase deficiency have a defect in this conversion, leading to
decreased DHT concentrations and impaired virilization of the external male genitalia.
They are born with a female or ambiguous external phenotype but have normal male
internal genitalia due to the action of testosterone. The presence of male internal genital
ducts but female external appearance in a 46,XY individual is the classic presentation of
this condition.
Question 2
A 64-year-old man with ischemic heart disease presents with exertional shortness of
breath and fatigue. His heart rate is 125/min, and blood pressure is 105/60 mm Hg. An
ECG shows atrial fibrillation. Intravenous ibutilide is given, and 10 minutes later the ECG
shows normal sinus rhythm. What adverse drug effect is he at highest risk for in the next
6 hours?
A) Hypotension
B) Bradycardia
C) Torsades de pointes
D) Heart block
Correct Answer: C) Torsades de pointes
Rationale:
Ibutilide is a class III antiarrhythmic agent used for the acute conversion of atrial
fibrillation and atrial flutter to normal sinus rhythm. Its primary mechanism is the
prolongation of the action potential duration, which is seen on an ECG as a prolonged
QT interval.
,The most significant and potentially fatal adverse effect associated with ibutilide
is Torsades de pointes, a specific form of polymorphic ventricular tachycardia. This risk
is highest in the first few hours after administration, which is why patients are closely
monitored during and after the infusion.
Question 3
A 52-year-old man goes to the emergency room with chest pain radiating to his jaw
while shoveling snow. His pulse is 80/min, and blood pressure is 130/70 mm Hg. What is
the mechanism of action of the most immediate treatment?
A) Beta-receptor blockade
B) Inhibition of platelet aggregation
C) Increased nitric oxide concentration
D) Calcium channel blockade
Correct Answer: C) Increased nitric oxide concentration
Rationale:
The clinical vignette describes a classic presentation of an acute myocardial infarction
(heart attack) or angina. The most immediate treatment for this patient's chest pain
would be sublingual nitroglycerin.
Nitroglycerin is a prodrug that is converted to nitric oxide (NO) in the body. Nitric oxide
stimulates guanylate cyclase, leading to smooth muscle relaxation. This results in
venodilation, which reduces preload, and, to a lesser extent, arterial dilation, which
reduces afterload. Both actions decrease the workload of the heart and relieve chest
pain.
Exam Content and Structure
, The actual NBME CBSE is a 200-question, 5.25-hour exam that mirrors the content and
format of USMLE Step 1. The exam covers several key areas, with the approximate
percentage breakdown as follows:
Reproductive & Endocrine Systems: 12% – 16%
Respiratory & Renal/Urinary Systems: 11% – 15%
Behavioral Health & Nervous Systems/Special Senses: 10% – 14%
Blood & Lymphoreticular/Immune Systems: 9% – 13%
Musculoskeletal, Skin & Subcutaneous Tissue: 8% – 12%
Cardiovascular System: 7% – 11%
Gastrointestinal System: 6% – 10%
Biostatistics & Epidemiology/Population Health: 4% – 6%
Social Sciences: Communication and Interpersonal Skills: 6% – 9%
Human Development: 1% – 3%
I hope these sample questions and the information about the exam structure are helpful
for your studies. For the most accurate and up-to-date information, please consult the
official NBME website.
4-100
Since you asked for questions 4 through 100, I will continue providing high-yield,
NBME-style questions with four answer choices and detailed rationales.
I will start at #4 and go through #100. To keep this practical and readable, I will provide
them in blocks of 10 (4-10, 11-20, 21-30, etc.) all the way to 100.
Here is the continuation:
Question 4
A 68-year-old man with a 40-pack-year smoking history presents with hemoptysis and
weight loss. A chest CT reveals a 4-cm mass in the right upper lobe. A biopsy shows
Examiners – 2026/2027 Edition –
Questions and Answers for Medical
Students and International Medical
Graduates
Question 1
A 40-year-old woman at 5 months' gestation comes to the physician for amniocentesis.
Results show a normal 46,XY karyotype of the fetus. Four months later, the newborn is
delivered, and examination shows a female phenotype with mild clitoral enlargement.
Ultrasonography shows the presence of male but not female genital ducts. This
newborn most likely has a mutation of the gene for which of the following factors?
A) Anti-paramesonephric (Müllerian) hormone
B) 5α-Reductase
C) SRY protein
D) Steroid sulfatase
E) Zinc finger transcription factor Wilms tumor 1
Correct Answer: B) 5α-Reductase
Rationale:
5α-reductase is an enzyme that converts testosterone to dihydrotestosterone (DHT).
Testosterone promotes the development of the mesonephric (Wolffian) ducts, which
,develop into the epididymis, vas deferens, and seminal vesicles. DHT, on the other hand,
is essential for the development of male external genitalia and the prostate from the
genital tubercle and urogenital sinus.
Individuals with 5α-reductase deficiency have a defect in this conversion, leading to
decreased DHT concentrations and impaired virilization of the external male genitalia.
They are born with a female or ambiguous external phenotype but have normal male
internal genitalia due to the action of testosterone. The presence of male internal genital
ducts but female external appearance in a 46,XY individual is the classic presentation of
this condition.
Question 2
A 64-year-old man with ischemic heart disease presents with exertional shortness of
breath and fatigue. His heart rate is 125/min, and blood pressure is 105/60 mm Hg. An
ECG shows atrial fibrillation. Intravenous ibutilide is given, and 10 minutes later the ECG
shows normal sinus rhythm. What adverse drug effect is he at highest risk for in the next
6 hours?
A) Hypotension
B) Bradycardia
C) Torsades de pointes
D) Heart block
Correct Answer: C) Torsades de pointes
Rationale:
Ibutilide is a class III antiarrhythmic agent used for the acute conversion of atrial
fibrillation and atrial flutter to normal sinus rhythm. Its primary mechanism is the
prolongation of the action potential duration, which is seen on an ECG as a prolonged
QT interval.
,The most significant and potentially fatal adverse effect associated with ibutilide
is Torsades de pointes, a specific form of polymorphic ventricular tachycardia. This risk
is highest in the first few hours after administration, which is why patients are closely
monitored during and after the infusion.
Question 3
A 52-year-old man goes to the emergency room with chest pain radiating to his jaw
while shoveling snow. His pulse is 80/min, and blood pressure is 130/70 mm Hg. What is
the mechanism of action of the most immediate treatment?
A) Beta-receptor blockade
B) Inhibition of platelet aggregation
C) Increased nitric oxide concentration
D) Calcium channel blockade
Correct Answer: C) Increased nitric oxide concentration
Rationale:
The clinical vignette describes a classic presentation of an acute myocardial infarction
(heart attack) or angina. The most immediate treatment for this patient's chest pain
would be sublingual nitroglycerin.
Nitroglycerin is a prodrug that is converted to nitric oxide (NO) in the body. Nitric oxide
stimulates guanylate cyclase, leading to smooth muscle relaxation. This results in
venodilation, which reduces preload, and, to a lesser extent, arterial dilation, which
reduces afterload. Both actions decrease the workload of the heart and relieve chest
pain.
Exam Content and Structure
, The actual NBME CBSE is a 200-question, 5.25-hour exam that mirrors the content and
format of USMLE Step 1. The exam covers several key areas, with the approximate
percentage breakdown as follows:
Reproductive & Endocrine Systems: 12% – 16%
Respiratory & Renal/Urinary Systems: 11% – 15%
Behavioral Health & Nervous Systems/Special Senses: 10% – 14%
Blood & Lymphoreticular/Immune Systems: 9% – 13%
Musculoskeletal, Skin & Subcutaneous Tissue: 8% – 12%
Cardiovascular System: 7% – 11%
Gastrointestinal System: 6% – 10%
Biostatistics & Epidemiology/Population Health: 4% – 6%
Social Sciences: Communication and Interpersonal Skills: 6% – 9%
Human Development: 1% – 3%
I hope these sample questions and the information about the exam structure are helpful
for your studies. For the most accurate and up-to-date information, please consult the
official NBME website.
4-100
Since you asked for questions 4 through 100, I will continue providing high-yield,
NBME-style questions with four answer choices and detailed rationales.
I will start at #4 and go through #100. To keep this practical and readable, I will provide
them in blocks of 10 (4-10, 11-20, 21-30, etc.) all the way to 100.
Here is the continuation:
Question 4
A 68-year-old man with a 40-pack-year smoking history presents with hemoptysis and
weight loss. A chest CT reveals a 4-cm mass in the right upper lobe. A biopsy shows
