2026/2027 COMSAE PHASE 1 FORM 113
ACTUAL EXAM QUESTIONS AND
DETAILED SOLUTIONS JUST
RELEASED.PDF
Core Domains
Osteopathic Principles and Practice (OPP)
Anatomy and Embryology
Physiology and Pathophysiology
Biochemistry and Molecular Biology
Microbiology and Immunology
Pharmacology and Pharmacotherapeutics
Pathology and Laboratory Medicine
Behavioral Science and Public Health
Introduction
The COMSAE Phase 1 Form 113 Examination evaluates the osteopathic medical
student's readiness for the COMLEX-USA Level 1 assessment. The examination
measures foundational biomedical science knowledge integrated with osteopathic
principles and clinical reasoning. Content emphasizes the application of scientific
mechanisms to patient presentations, requiring candidates to analyze clinical
vignettes and select the most appropriate diagnosis, mechanism, or management
strategy. This comprehensive test bank challenges the candidate to demonstrate
mastery across anatomy, physiology, biochemistry, microbiology, pharmacology,
pathology, and behavioral science, preparing the osteopathic medical student for
success on the COMLEX-USA Level 1 and in clinical practice.
SECTION ONE: QUESTIONS 1–100
1. A 24-year-old woman presents with fatigue, weight loss, heat intolerance,
palpitations, and a fine tremor. Examination reveals a diffusely enlarged thyroid
,and bilateral exophthalmos. Laboratory studies show decreased TSH and
increased free T4. Which mechanism best explains her condition?
A. Destruction of thyroid follicles by cytotoxic T cells
B. Activation of the TSH receptor by stimulating immunoglobulin
C. Autonomous secretion of TSH by a pituitary adenoma
D. Inhibition of thyroid peroxidase by circulating antibodies
B. Activation of the TSH receptor by stimulating immunoglobulin
RATIONALE: Graves disease is caused by thyroid-stimulating immunoglobulin
that binds and activates the TSH receptor, resulting in increased thyroid hormone
synthesis and diffuse thyroid enlargement. Ophthalmopathy is also characteristic.
2. A 67-year-old man with hypertension develops sudden right-sided weakness
and difficulty speaking. He is found to have atrial fibrillation. MRI demonstrates
an acute infarction involving the left middle cerebral artery territory. Which
vascular structure is most likely occluded?
A. Left anterior cerebral artery
B. Left posterior cerebral artery
C. Left middle cerebral artery
D. Basilar artery
C. Left middle cerebral artery
RATIONALE: The middle cerebral artery supplies much of the lateral cerebral
hemisphere. A dominant-hemisphere MCA infarction commonly produces
contralateral weakness, sensory deficits, and aphasia. Atrial fibrillation increases
the risk of embolic ischemic stroke.
3. A 5-year-old child presents with fever, sore throat, tender anterior cervical
lymphadenopathy, and tonsillar exudates without cough. Which organism is
the most likely cause?
A. Corynebacterium diphtheriae
B. Epstein-Barr virus
,C. Streptococcus pyogenes
D. Haemophilus influenzae
C. Streptococcus pyogenes
RATIONALE: Streptococcus pyogenes causes group A streptococcal
pharyngitis, which classically presents with fever, tonsillar exudates, tender anterior
cervical nodes, and absence of cough.
4. A 58-year-old man experiences crushing substernal chest pain radiating to
his left arm. ECG demonstrates ST-segment elevation in leads II, III, and aVF.
Which coronary artery is most likely occluded?
A. Left anterior descending artery
B. Left circumflex artery
C. Right coronary artery
D. Left main coronary artery
C. Right coronary artery
RATIONALE: ST-segment elevation in leads II, III, and aVF indicates an inferior
myocardial infarction. The right coronary artery is the most common culprit vessel
in inferior STEMI.
5. A patient with chronic obstructive pulmonary disease develops worsening
dyspnea and increased sputum production. Which pulmonary finding is most
consistent with emphysema?
A. Decreased total lung capacity
B. Decreased residual volume
C. Increased lung compliance
D. Increased elastic recoil
C. Increased lung compliance
RATIONALE: Emphysema involves destruction of alveolar walls and elastic
tissue, causing increased lung compliance and decreased elastic recoil. Air trapping
leads to increased residual volume and total lung capacity.
, 6. A 32-year-old woman develops painful swelling of the left calf 1 week after
surgery. Doppler ultrasonography confirms a deep venous thrombosis. Which
component of Virchow triad most directly explains her postoperative risk?
A. Hypercalcemia
B. Venous stasis
C. Increased arterial flow
D. Thrombocytopenia
B. Venous stasis
RATIONALE: Virchow triad consists of endothelial injury, abnormal blood flow
such as stasis, and hypercoagulability. Immobilization after surgery promotes
venous stasis and increases the risk of DVT.
7. A 27-year-old woman presents with fatigue, paresthesias of the feet, and
difficulty maintaining balance. Laboratory studies show macrocytic anemia
and an elevated methylmalonic acid level. Which biochemical reaction is most
directly impaired in this patient?
A. Conversion of homocysteine to methionine
B. Conversion of methylmalonyl-CoA to succinyl-CoA
C. Conversion of pyruvate to acetyl-CoA
D. Conversion of ribose-5-phosphate to phosphoribosyl pyrophosphate
B. Conversion of methylmalonyl-CoA to succinyl-CoA
RATIONALE: Vitamin B12 is required as a cofactor for methylmalonyl-CoA
mutase, which converts methylmalonyl-CoA to succinyl-CoA. Vitamin B12
deficiency therefore causes elevated methylmalonic acid and can produce
neurologic manifestations such as paresthesias and impaired proprioception.
Folate and vitamin B12 deficiencies can both cause megaloblastic anemia, but only
B12 deficiency causes elevated methylmalonic acid.
8. A 64-year-old man develops sudden weakness of the right face and right
upper and lower extremities. He also has difficulty speaking. Imaging reveals
ACTUAL EXAM QUESTIONS AND
DETAILED SOLUTIONS JUST
RELEASED.PDF
Core Domains
Osteopathic Principles and Practice (OPP)
Anatomy and Embryology
Physiology and Pathophysiology
Biochemistry and Molecular Biology
Microbiology and Immunology
Pharmacology and Pharmacotherapeutics
Pathology and Laboratory Medicine
Behavioral Science and Public Health
Introduction
The COMSAE Phase 1 Form 113 Examination evaluates the osteopathic medical
student's readiness for the COMLEX-USA Level 1 assessment. The examination
measures foundational biomedical science knowledge integrated with osteopathic
principles and clinical reasoning. Content emphasizes the application of scientific
mechanisms to patient presentations, requiring candidates to analyze clinical
vignettes and select the most appropriate diagnosis, mechanism, or management
strategy. This comprehensive test bank challenges the candidate to demonstrate
mastery across anatomy, physiology, biochemistry, microbiology, pharmacology,
pathology, and behavioral science, preparing the osteopathic medical student for
success on the COMLEX-USA Level 1 and in clinical practice.
SECTION ONE: QUESTIONS 1–100
1. A 24-year-old woman presents with fatigue, weight loss, heat intolerance,
palpitations, and a fine tremor. Examination reveals a diffusely enlarged thyroid
,and bilateral exophthalmos. Laboratory studies show decreased TSH and
increased free T4. Which mechanism best explains her condition?
A. Destruction of thyroid follicles by cytotoxic T cells
B. Activation of the TSH receptor by stimulating immunoglobulin
C. Autonomous secretion of TSH by a pituitary adenoma
D. Inhibition of thyroid peroxidase by circulating antibodies
B. Activation of the TSH receptor by stimulating immunoglobulin
RATIONALE: Graves disease is caused by thyroid-stimulating immunoglobulin
that binds and activates the TSH receptor, resulting in increased thyroid hormone
synthesis and diffuse thyroid enlargement. Ophthalmopathy is also characteristic.
2. A 67-year-old man with hypertension develops sudden right-sided weakness
and difficulty speaking. He is found to have atrial fibrillation. MRI demonstrates
an acute infarction involving the left middle cerebral artery territory. Which
vascular structure is most likely occluded?
A. Left anterior cerebral artery
B. Left posterior cerebral artery
C. Left middle cerebral artery
D. Basilar artery
C. Left middle cerebral artery
RATIONALE: The middle cerebral artery supplies much of the lateral cerebral
hemisphere. A dominant-hemisphere MCA infarction commonly produces
contralateral weakness, sensory deficits, and aphasia. Atrial fibrillation increases
the risk of embolic ischemic stroke.
3. A 5-year-old child presents with fever, sore throat, tender anterior cervical
lymphadenopathy, and tonsillar exudates without cough. Which organism is
the most likely cause?
A. Corynebacterium diphtheriae
B. Epstein-Barr virus
,C. Streptococcus pyogenes
D. Haemophilus influenzae
C. Streptococcus pyogenes
RATIONALE: Streptococcus pyogenes causes group A streptococcal
pharyngitis, which classically presents with fever, tonsillar exudates, tender anterior
cervical nodes, and absence of cough.
4. A 58-year-old man experiences crushing substernal chest pain radiating to
his left arm. ECG demonstrates ST-segment elevation in leads II, III, and aVF.
Which coronary artery is most likely occluded?
A. Left anterior descending artery
B. Left circumflex artery
C. Right coronary artery
D. Left main coronary artery
C. Right coronary artery
RATIONALE: ST-segment elevation in leads II, III, and aVF indicates an inferior
myocardial infarction. The right coronary artery is the most common culprit vessel
in inferior STEMI.
5. A patient with chronic obstructive pulmonary disease develops worsening
dyspnea and increased sputum production. Which pulmonary finding is most
consistent with emphysema?
A. Decreased total lung capacity
B. Decreased residual volume
C. Increased lung compliance
D. Increased elastic recoil
C. Increased lung compliance
RATIONALE: Emphysema involves destruction of alveolar walls and elastic
tissue, causing increased lung compliance and decreased elastic recoil. Air trapping
leads to increased residual volume and total lung capacity.
, 6. A 32-year-old woman develops painful swelling of the left calf 1 week after
surgery. Doppler ultrasonography confirms a deep venous thrombosis. Which
component of Virchow triad most directly explains her postoperative risk?
A. Hypercalcemia
B. Venous stasis
C. Increased arterial flow
D. Thrombocytopenia
B. Venous stasis
RATIONALE: Virchow triad consists of endothelial injury, abnormal blood flow
such as stasis, and hypercoagulability. Immobilization after surgery promotes
venous stasis and increases the risk of DVT.
7. A 27-year-old woman presents with fatigue, paresthesias of the feet, and
difficulty maintaining balance. Laboratory studies show macrocytic anemia
and an elevated methylmalonic acid level. Which biochemical reaction is most
directly impaired in this patient?
A. Conversion of homocysteine to methionine
B. Conversion of methylmalonyl-CoA to succinyl-CoA
C. Conversion of pyruvate to acetyl-CoA
D. Conversion of ribose-5-phosphate to phosphoribosyl pyrophosphate
B. Conversion of methylmalonyl-CoA to succinyl-CoA
RATIONALE: Vitamin B12 is required as a cofactor for methylmalonyl-CoA
mutase, which converts methylmalonyl-CoA to succinyl-CoA. Vitamin B12
deficiency therefore causes elevated methylmalonic acid and can produce
neurologic manifestations such as paresthesias and impaired proprioception.
Folate and vitamin B12 deficiencies can both cause megaloblastic anemia, but only
B12 deficiency causes elevated methylmalonic acid.
8. A 64-year-old man develops sudden weakness of the right face and right
upper and lower extremities. He also has difficulty speaking. Imaging reveals
