COMSAE Phase 2–Style Practice Exam –
Form 106b (Original Practice Set) Exam
Questions With Correct Answers
(Verified Answers) Plus Rationales 2026
Q&A | Instant Download Pdf.
1. A 67-year-old man with a history of hypertension presents with
sudden-onset chest pain radiating to the back. Blood pressure is
180/100 in the right arm and 150/90 in the left arm. Which is the
most likely diagnosis?
A. Acute myocardial infarction
B. Pulmonary embolism
C. Aortic dissection
D. Pericarditis
Answer: C. Aortic dissection
Rationale: The sudden tearing chest pain radiating to the back
combined with unequal blood pressures between arms is classic
for aortic dissection, often due to uncontrolled hypertension
causing intimal tear and propagation of blood within the aortic
wall.
2. A 24-year-old woman presents with heat intolerance, weight loss,
and palpitations. Labs show low TSH and elevated free T4. What is
the most likely cause?
, A. Hashimoto thyroiditis
B. Graves disease
C. Thyroid carcinoma
D. Subacute thyroiditis
Answer: B. Graves disease
Rationale: Hyperthyroidism with suppressed TSH and elevated T4
in a young woman is most commonly due to Graves disease, an
autoimmune condition involving TSH receptor–stimulating
antibodies.
3. A patient presents with tremor at rest, bradykinesia, and rigidity.
Which brain structure is most affected?
A. Caudate nucleus
B. Substantia nigra
C. Hippocampus
D. Cerebellar cortex
Answer: B. Substantia nigra
Rationale: Parkinson disease results from degeneration of
dopaminergic neurons in the substantia nigra pars compacta.
4. A 5-year-old child presents with fever, barking cough, and
inspiratory stridor. What is the most likely diagnosis?
A. Epiglottitis
B. Asthma
C. Croup
D. Bronchiolitis
Answer: C. Croup
, Rationale: Parainfluenza virus causes laryngotracheobronchitis
(croup), characterized by a barking cough and inspiratory stridor.
5. A patient with COPD is given oxygen therapy and develops
worsening hypercapnia. What is the primary mechanism?
A. Increased CO2 production
B. Haldane effect only
C. Loss of hypoxic respiratory drive
D. Decreased tidal volume from anxiety
Answer: C. Loss of hypoxic respiratory drive
Rationale: In chronic CO2 retainers, high oxygen can reduce
respiratory drive mediated by peripheral chemoreceptors.
6. A newborn has cyanosis that improves with prostaglandin E1
infusion. What condition is most likely?
A. Tetralogy of Fallot
B. Transposition of the great arteries
C. Ventricular septal defect
D. Patent ductus arteriosus
Answer: B. Transposition of the great arteries
Rationale: TGA requires a patent ductus arteriosus to maintain
mixing of oxygenated and deoxygenated blood; prostaglandin E1
keeps ductus open.
7. Which electrolyte abnormality is most associated with Torsades de
Pointes?
, A. Hypercalcemia
B. Hypokalemia
C. Hypernatremia
D. Hypermagnesemia
Answer: B. Hypokalemia
Rationale: Low potassium prolongs repolarization and QT interval,
predisposing to torsades de pointes.
8. A patient has hematuria and RBC casts in urine. Where is the
lesion located?
A. Bladder
B. Ureter
C. Glomerulus
D. Prostate
Answer: C. Glomerulus
Rationale: RBC casts are highly specific for glomerular bleeding.
9. A 30-year-old woman has malar rash, photosensitivity, and anti-
dsDNA antibodies. What is the diagnosis?
A. Rheumatoid arthritis
B. Systemic lupus erythematosus
C. Scleroderma
D. Sjögren syndrome
Answer: B. Systemic lupus erythematosus
Rationale: Anti-dsDNA and malar rash are classic for SLE.
Form 106b (Original Practice Set) Exam
Questions With Correct Answers
(Verified Answers) Plus Rationales 2026
Q&A | Instant Download Pdf.
1. A 67-year-old man with a history of hypertension presents with
sudden-onset chest pain radiating to the back. Blood pressure is
180/100 in the right arm and 150/90 in the left arm. Which is the
most likely diagnosis?
A. Acute myocardial infarction
B. Pulmonary embolism
C. Aortic dissection
D. Pericarditis
Answer: C. Aortic dissection
Rationale: The sudden tearing chest pain radiating to the back
combined with unequal blood pressures between arms is classic
for aortic dissection, often due to uncontrolled hypertension
causing intimal tear and propagation of blood within the aortic
wall.
2. A 24-year-old woman presents with heat intolerance, weight loss,
and palpitations. Labs show low TSH and elevated free T4. What is
the most likely cause?
, A. Hashimoto thyroiditis
B. Graves disease
C. Thyroid carcinoma
D. Subacute thyroiditis
Answer: B. Graves disease
Rationale: Hyperthyroidism with suppressed TSH and elevated T4
in a young woman is most commonly due to Graves disease, an
autoimmune condition involving TSH receptor–stimulating
antibodies.
3. A patient presents with tremor at rest, bradykinesia, and rigidity.
Which brain structure is most affected?
A. Caudate nucleus
B. Substantia nigra
C. Hippocampus
D. Cerebellar cortex
Answer: B. Substantia nigra
Rationale: Parkinson disease results from degeneration of
dopaminergic neurons in the substantia nigra pars compacta.
4. A 5-year-old child presents with fever, barking cough, and
inspiratory stridor. What is the most likely diagnosis?
A. Epiglottitis
B. Asthma
C. Croup
D. Bronchiolitis
Answer: C. Croup
, Rationale: Parainfluenza virus causes laryngotracheobronchitis
(croup), characterized by a barking cough and inspiratory stridor.
5. A patient with COPD is given oxygen therapy and develops
worsening hypercapnia. What is the primary mechanism?
A. Increased CO2 production
B. Haldane effect only
C. Loss of hypoxic respiratory drive
D. Decreased tidal volume from anxiety
Answer: C. Loss of hypoxic respiratory drive
Rationale: In chronic CO2 retainers, high oxygen can reduce
respiratory drive mediated by peripheral chemoreceptors.
6. A newborn has cyanosis that improves with prostaglandin E1
infusion. What condition is most likely?
A. Tetralogy of Fallot
B. Transposition of the great arteries
C. Ventricular septal defect
D. Patent ductus arteriosus
Answer: B. Transposition of the great arteries
Rationale: TGA requires a patent ductus arteriosus to maintain
mixing of oxygenated and deoxygenated blood; prostaglandin E1
keeps ductus open.
7. Which electrolyte abnormality is most associated with Torsades de
Pointes?
, A. Hypercalcemia
B. Hypokalemia
C. Hypernatremia
D. Hypermagnesemia
Answer: B. Hypokalemia
Rationale: Low potassium prolongs repolarization and QT interval,
predisposing to torsades de pointes.
8. A patient has hematuria and RBC casts in urine. Where is the
lesion located?
A. Bladder
B. Ureter
C. Glomerulus
D. Prostate
Answer: C. Glomerulus
Rationale: RBC casts are highly specific for glomerular bleeding.
9. A 30-year-old woman has malar rash, photosensitivity, and anti-
dsDNA antibodies. What is the diagnosis?
A. Rheumatoid arthritis
B. Systemic lupus erythematosus
C. Scleroderma
D. Sjögren syndrome
Answer: B. Systemic lupus erythematosus
Rationale: Anti-dsDNA and malar rash are classic for SLE.
