COMSAE LEVEL 1 — FORM B PRACTICE
QUESTIONS AND CORRECT ANSWERS
(VERIFIED ANSWERS) PLUS RATIONALES 2026
Q&A | INSTANT DOWNLOAD PDF
1. A 24-year-old man presents with fever, sore throat, posterior
cervical lymphadenopathy, and fatigue. Heterophile antibody test
is positive. Which of the following is the most likely causative
agent?
A. Group A Streptococcus
B. Cytomegalovirus
C. Epstein–Barr virus
D. Human immunodeficiency virus
E. Adenovirus
Rationale: Infectious mononucleosis with heterophile Ab
positivity is typically due to EBV, a herpesvirus that infects B
cells.
2. A 60-year-old man with a long smoking history has progressive
exertional dyspnea and decreased DLCO on PFTs. Which process
best explains his gas transfer abnormality?
A. Airway hyperresponsiveness
B. Mucus plugging
C. Destruction of alveolar walls leading to decreased alveolar-
capillary surface area
D. Increased bronchial smooth muscle mass
E. Pulmonary vascular occlusion
, Rationale: Emphysema from smoking destroys alveolar walls,
reducing surface area and lowering DLCO.
3. A newborn has a holosystolic murmur best heard at the left lower
sternal border and failure to thrive. Echo shows a ventricular
septal defect. Which embryologic structure failed to form
properly?
A. Endocardial cushions only
B. Muscular and membranous interventricular septum formation
(IV septum components)
C. Truncus arteriosus septation
D. Foramen ovale closure
E. Ductus arteriosus persistence
Rationale: VSDs result from maldevelopment of the
interventricular septum (membranous or muscular portions).
4. A patient on a thiazide diuretic develops hyperglycemia and
hyperuricemia. Which mechanism explains the uric acid
elevation?
A. Increased uric acid production
B. Decreased xanthine oxidase activity
C. Reduced renal uric acid excretion due to volume contraction
and competition in proximal tubule
D. Increased tubular secretion of uric acid
E. Direct stimulation of uric acid synthesis in liver
Rationale: Thiazides cause volume depletion and compete for
proximal tubular secretion, reducing uric acid excretion.
5. A 5-year-old boy presents with recurrent otitis media, nasal
polyps, and atopic dermatitis. Which immunoglobulin is most
likely elevated?
A. IgA
, B. IgG
C. IgM
D. IgE
E. IgD
Rationale: Atopic conditions and nasal polyps are associated
with IgE-mediated allergic responses.
6. A 30-year-old woman with Graves disease has heat intolerance,
weight loss, and exophthalmos. Which antibody is most specific to
her condition?
A. Anti-thyroid peroxidase (anti-TPO) only
B. Anti-thyroglobulin only
C. Thyroid-stimulating immunoglobulin (TSI) that stimulates TSH
receptor
D. Anti-TSH receptor blocking antibody
E. Anti-TSH antibody
Rationale: Graves is caused by TSI (stimulating TSH receptor)
producing hyperthyroidism and ophthalmopathy.
7. A 45-year-old man presents with progressive upper motor neuron
signs and lower motor neuron signs. Which disease best fits this
combination?
A. Multiple sclerosis
B. Guillain–Barré syndrome
C. Amyotrophic lateral sclerosis (ALS)
D. Myasthenia gravis
E. Spinal muscular atrophy
Rationale: ALS affects both UMN and LMN leading to mixed
findings; other diseases usually affect one or the other.
8. A patient has an anion gap metabolic acidosis with elevated
serum ketones. Which laboratory finding supports diabetic
, ketoacidosis over alcoholic ketoacidosis?
A. Low glucose
B. Markedly elevated glucose
C. High bicarbonate
D. High pH
E. Low serum osmolality
Rationale: DKA presents with hyperglycemia; alcoholic
ketoacidosis typically has normal or low glucose.
9. A 70-year-old man has asymmetrical osteoarthritis in DIP joints
with Heberden nodes. Which cartilage change is characteristic?
A. Immune complex deposition
B. Uniform cartilage thickening
C. Focal cartilage erosion and subchondral bone remodeling
D. Synovial pannus formation
E. Mononuclear infiltrate with vasculitis
Rationale: Osteoarthritis involves focal cartilage loss and
subchondral bone changes; pannus is RA.
10. A 22-year-old woman with severe abdominal pain after a
binge presents with elevated serum amylase and lipase. What is
the most common cause in young adults?
A. Gallstones
B. Alcohol binge
C. Medication-related only
D. Hypertriglyceridemia exclusively
E. Autoimmune pancreatitis
Rationale: In young adults, alcohol (binge) is a common cause
along with gallstones; many causes exist.
11. A 35-year-old male presents with decreased sensation in a
"glove and stocking" distribution and absent ankle reflexes. Which
QUESTIONS AND CORRECT ANSWERS
(VERIFIED ANSWERS) PLUS RATIONALES 2026
Q&A | INSTANT DOWNLOAD PDF
1. A 24-year-old man presents with fever, sore throat, posterior
cervical lymphadenopathy, and fatigue. Heterophile antibody test
is positive. Which of the following is the most likely causative
agent?
A. Group A Streptococcus
B. Cytomegalovirus
C. Epstein–Barr virus
D. Human immunodeficiency virus
E. Adenovirus
Rationale: Infectious mononucleosis with heterophile Ab
positivity is typically due to EBV, a herpesvirus that infects B
cells.
2. A 60-year-old man with a long smoking history has progressive
exertional dyspnea and decreased DLCO on PFTs. Which process
best explains his gas transfer abnormality?
A. Airway hyperresponsiveness
B. Mucus plugging
C. Destruction of alveolar walls leading to decreased alveolar-
capillary surface area
D. Increased bronchial smooth muscle mass
E. Pulmonary vascular occlusion
, Rationale: Emphysema from smoking destroys alveolar walls,
reducing surface area and lowering DLCO.
3. A newborn has a holosystolic murmur best heard at the left lower
sternal border and failure to thrive. Echo shows a ventricular
septal defect. Which embryologic structure failed to form
properly?
A. Endocardial cushions only
B. Muscular and membranous interventricular septum formation
(IV septum components)
C. Truncus arteriosus septation
D. Foramen ovale closure
E. Ductus arteriosus persistence
Rationale: VSDs result from maldevelopment of the
interventricular septum (membranous or muscular portions).
4. A patient on a thiazide diuretic develops hyperglycemia and
hyperuricemia. Which mechanism explains the uric acid
elevation?
A. Increased uric acid production
B. Decreased xanthine oxidase activity
C. Reduced renal uric acid excretion due to volume contraction
and competition in proximal tubule
D. Increased tubular secretion of uric acid
E. Direct stimulation of uric acid synthesis in liver
Rationale: Thiazides cause volume depletion and compete for
proximal tubular secretion, reducing uric acid excretion.
5. A 5-year-old boy presents with recurrent otitis media, nasal
polyps, and atopic dermatitis. Which immunoglobulin is most
likely elevated?
A. IgA
, B. IgG
C. IgM
D. IgE
E. IgD
Rationale: Atopic conditions and nasal polyps are associated
with IgE-mediated allergic responses.
6. A 30-year-old woman with Graves disease has heat intolerance,
weight loss, and exophthalmos. Which antibody is most specific to
her condition?
A. Anti-thyroid peroxidase (anti-TPO) only
B. Anti-thyroglobulin only
C. Thyroid-stimulating immunoglobulin (TSI) that stimulates TSH
receptor
D. Anti-TSH receptor blocking antibody
E. Anti-TSH antibody
Rationale: Graves is caused by TSI (stimulating TSH receptor)
producing hyperthyroidism and ophthalmopathy.
7. A 45-year-old man presents with progressive upper motor neuron
signs and lower motor neuron signs. Which disease best fits this
combination?
A. Multiple sclerosis
B. Guillain–Barré syndrome
C. Amyotrophic lateral sclerosis (ALS)
D. Myasthenia gravis
E. Spinal muscular atrophy
Rationale: ALS affects both UMN and LMN leading to mixed
findings; other diseases usually affect one or the other.
8. A patient has an anion gap metabolic acidosis with elevated
serum ketones. Which laboratory finding supports diabetic
, ketoacidosis over alcoholic ketoacidosis?
A. Low glucose
B. Markedly elevated glucose
C. High bicarbonate
D. High pH
E. Low serum osmolality
Rationale: DKA presents with hyperglycemia; alcoholic
ketoacidosis typically has normal or low glucose.
9. A 70-year-old man has asymmetrical osteoarthritis in DIP joints
with Heberden nodes. Which cartilage change is characteristic?
A. Immune complex deposition
B. Uniform cartilage thickening
C. Focal cartilage erosion and subchondral bone remodeling
D. Synovial pannus formation
E. Mononuclear infiltrate with vasculitis
Rationale: Osteoarthritis involves focal cartilage loss and
subchondral bone changes; pannus is RA.
10. A 22-year-old woman with severe abdominal pain after a
binge presents with elevated serum amylase and lipase. What is
the most common cause in young adults?
A. Gallstones
B. Alcohol binge
C. Medication-related only
D. Hypertriglyceridemia exclusively
E. Autoimmune pancreatitis
Rationale: In young adults, alcohol (binge) is a common cause
along with gallstones; many causes exist.
11. A 35-year-old male presents with decreased sensation in a
"glove and stocking" distribution and absent ankle reflexes. Which
