2026 Comprehensive Osteopathic Medical
Self-Assessment Examination (COMSAE) |
Verified Practice Questions with Detailed
Rationales & Answers
Question 1
A 26-year-old woman presents with fatigue, dark urine, and
jaundice one week after receiving trimethoprim-
sulfamethoxazole for a urinary tract infection. Physical
examination reveals mild scleral icterus. Laboratory studies
show:
Hemoglobin: 8.9 g/dL
Reticulocyte count: Elevated
Indirect bilirubin: Elevated
LDH: Elevated
Haptoglobin: Decreased
Peripheral smear demonstrates numerous bite cells.
Which enzyme deficiency best explains this patient's condition?
A. Pyruvate kinase
,B. Glucose-6-phosphate dehydrogenase
C. Spectrin
D. Hexokinase
E. Ferrochelatase
Answer: B. Glucose-6-phosphate dehydrogenase
Rationale: G6PD deficiency predisposes erythrocytes to
oxidative injury following sulfonamides, dapsone, primaquine,
or fava beans. Heinz bodies are removed by splenic
macrophages producing bite cells. Pyruvate kinase deficiency
causes echinocytes without oxidative triggers.
Question 2
A 63-year-old man develops severe substernal chest pain. ECG
demonstrates ST elevations in leads II, III, and aVF.
Twenty-four hours later he develops profound hypotension,
elevated jugular venous pressure, and clear lungs.
Which structure is most likely infarcted?
A. Left ventricle
B. Papillary muscle
C. Right ventricle
,D. Left atrium
E. Interventricular septum
Answer: C. Right ventricle
Rationale: Inferior myocardial infarction involving the right
coronary artery frequently extends into the right ventricle.
Right ventricular failure produces hypotension with elevated
JVP but minimal pulmonary edema.
Question 3
A researcher administers atropine to healthy volunteers.
Which physiologic change is most likely?
A. Increased salivation
B. Bradycardia
C. Mydriasis
D. Bronchoconstriction
E. Increased gastrointestinal motility
Answer: C. Mydriasis
Rationale: Atropine competitively blocks muscarinic receptors,
causing mydriasis, cycloplegia, tachycardia, urinary retention,
constipation, and decreased secretions.
, Question 4
A newborn develops vomiting shortly after initiation of
breastfeeding. Laboratory testing demonstrates
hyperammonemia and markedly elevated orotic acid with low
BUN.
Which enzyme is deficient?
A. Carbamoyl phosphate synthetase II
B. Ornithine transcarbamylase
C. Arginase
D. Argininosuccinate lyase
E. Argininosuccinate synthetase
Answer: B. Ornithine transcarbamylase
Rationale: OTC deficiency is the most common urea cycle
disorder and the only X-linked defect. Carbamoyl phosphate
accumulates and enters pyrimidine synthesis, increasing orotic
acid.
Question 5
Self-Assessment Examination (COMSAE) |
Verified Practice Questions with Detailed
Rationales & Answers
Question 1
A 26-year-old woman presents with fatigue, dark urine, and
jaundice one week after receiving trimethoprim-
sulfamethoxazole for a urinary tract infection. Physical
examination reveals mild scleral icterus. Laboratory studies
show:
Hemoglobin: 8.9 g/dL
Reticulocyte count: Elevated
Indirect bilirubin: Elevated
LDH: Elevated
Haptoglobin: Decreased
Peripheral smear demonstrates numerous bite cells.
Which enzyme deficiency best explains this patient's condition?
A. Pyruvate kinase
,B. Glucose-6-phosphate dehydrogenase
C. Spectrin
D. Hexokinase
E. Ferrochelatase
Answer: B. Glucose-6-phosphate dehydrogenase
Rationale: G6PD deficiency predisposes erythrocytes to
oxidative injury following sulfonamides, dapsone, primaquine,
or fava beans. Heinz bodies are removed by splenic
macrophages producing bite cells. Pyruvate kinase deficiency
causes echinocytes without oxidative triggers.
Question 2
A 63-year-old man develops severe substernal chest pain. ECG
demonstrates ST elevations in leads II, III, and aVF.
Twenty-four hours later he develops profound hypotension,
elevated jugular venous pressure, and clear lungs.
Which structure is most likely infarcted?
A. Left ventricle
B. Papillary muscle
C. Right ventricle
,D. Left atrium
E. Interventricular septum
Answer: C. Right ventricle
Rationale: Inferior myocardial infarction involving the right
coronary artery frequently extends into the right ventricle.
Right ventricular failure produces hypotension with elevated
JVP but minimal pulmonary edema.
Question 3
A researcher administers atropine to healthy volunteers.
Which physiologic change is most likely?
A. Increased salivation
B. Bradycardia
C. Mydriasis
D. Bronchoconstriction
E. Increased gastrointestinal motility
Answer: C. Mydriasis
Rationale: Atropine competitively blocks muscarinic receptors,
causing mydriasis, cycloplegia, tachycardia, urinary retention,
constipation, and decreased secretions.
, Question 4
A newborn develops vomiting shortly after initiation of
breastfeeding. Laboratory testing demonstrates
hyperammonemia and markedly elevated orotic acid with low
BUN.
Which enzyme is deficient?
A. Carbamoyl phosphate synthetase II
B. Ornithine transcarbamylase
C. Arginase
D. Argininosuccinate lyase
E. Argininosuccinate synthetase
Answer: B. Ornithine transcarbamylase
Rationale: OTC deficiency is the most common urea cycle
disorder and the only X-linked defect. Carbamoyl phosphate
accumulates and enters pyrimidine synthesis, increasing orotic
acid.
Question 5
