COMLEX LEVEL 1 COMSAE PHASE 1 (FORM
106) ACTUAL EXAM 2026 COMPLETE EXAM
QUESTIONS AND CORRECT DETAILED
ANSWERS A NEW UPDATED VERSION LATEST
2026-2027 (100% CORRECT VERIFIED ANSWERS)
ALREADY GRADED A+
1. A 55-year-old man presents with chest pain radiating to the left arm. ECG
shows ST 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. Posterior descending artery
Rationale: ST elevation in leads II, III, and aVF indicates an inferior myocardial
infarction. The right coronary artery supplies the inferior wall of the left ventricle
in most individuals (right-dominant circulation). LAD occlusion affects anterior
leads (V1-V4), while circumflex occlusion typically affects lateral leads (I, aVL,
V5-V6).
2. A 23-year-old woman presents with fatigue, pallor, and microcytic anemia.
Which laboratory finding is most consistent with iron deficiency anemia?
A. Increased ferritin
B. Decreased total iron-binding capacity
C. Increased transferrin saturation
D. Decreased ferritin
,Rationale: Ferritin reflects total body iron stores. In iron deficiency anemia,
ferritin is decreased, TIBC is typically increased, and transferrin saturation is
decreased. Microcytic hypochromic anemia with low ferritin is diagnostic.
3. A 45-year-old man with chronic alcohol use presents with confusion, ataxia,
and ophthalmoplegia. Which vitamin deficiency is most likely responsible?
A. Vitamin B3 (Niacin)
B. Vitamin B1 (Thiamine)
C. Vitamin B6 (Pyridoxine)
D. Vitamin B12 (Cobalamin)
Rationale: The classic triad of confusion, ataxia, and ophthalmoplegia is Wernicke
encephalopathy, caused by thiamine (Vitamin B1) deficiency. This is commonly
seen in chronic alcohol use disorder due to poor nutrition and impaired thiamine
absorption.
4. A patient presents with chronic cough and hemoptysis. Imaging shows a
cavitary lesion in the upper lobe. What is the most likely diagnosis?
A. Klebsiella pneumoniae
B. Tuberculosis
C. Streptococcus pneumoniae
D. Lung abscess
Rationale: Mycobacterium tuberculosis infection classically presents with cavitary
lesions in the upper lobes, chronic cough, hemoptysis, and constitutional
symptoms. Upper lobe involvement is due to high oxygen tension favoring
mycobacterial growth.
5. Which vitamin deficiency is associated with a prolonged PT/INR?
A. Vitamin A
B. Vitamin C
,C. Vitamin K
D. Vitamin D
Rationale: Vitamin K is required for the gamma-carboxylation of clotting factors
II, VII, IX, and X. Deficiency leads to impaired coagulation, prolonging PT/INR.
Warfarin inhibits vitamin K epoxide reductase, producing the same effect.
6. A 28-year-old woman presents with heat intolerance, weight loss,
palpitations, and exophthalmos. Laboratory testing reveals suppressed TSH
and elevated T4. What is the most likely diagnosis?
A. Hashimoto thyroiditis
B. Subacute thyroiditis
C. Graves disease
D. Thyroid adenoma
Rationale: Graves disease is an autoimmune disorder caused by TSH receptor-
stimulating antibodies, leading to hyperthyroidism with suppressed TSH and
elevated T3/T4. Exophthalmos is a characteristic finding. Hashimoto thyroiditis
causes hypothyroidism.
7. A patient develops severe watery diarrhea after taking antibiotics. Which
organism is most likely responsible?
A. Escherichia coli
B. Salmonella enterica
C. Clostridioides difficile
D. Shigella dysenteriae
Rationale: C. difficile infection is the most common cause of antibiotic-associated
diarrhea and pseudomembranous colitis. Toxins A and B cause mucosal
inflammation and watery diarrhea. Risk factors include recent antibiotic use,
particularly clindamycin, cephalosporins, and fluoroquinolones.
, 8. A 65-year-old man presents with a resting tremor, bradykinesia, and
cogwheel rigidity. Which neurotransmitter deficiency is the primary
pathophysiology?
A. Acetylcholine
B. Dopamine
C. Serotonin
D. GABA
Rationale: Parkinson disease is characterized by degeneration of dopaminergic
neurons in the substantia nigra pars compacta, leading to decreased dopamine in
the striatum. This causes the classic triad of resting tremor, bradykinesia, and
rigidity.
9. A patient with severe dehydration has increased ADH secretion. What is the
mechanism of ADH action?
A. Increases sodium reabsorption in proximal tubule
B. Increases water reabsorption in collecting ducts via aquaporin-2 insertion
C. Decreases urea permeability in inner medulla
D. Stimulates aldosterone secretion
Rationale: ADH (vasopressin) increases water permeability of principal cells in
the collecting ducts by promoting insertion of aquaporin-2 channels into the
luminal membrane. This allows water reabsorption and urine concentration.
10. Which immunoglobulin class crosses the placenta?
A. IgA
B. IgG
C. IgM
D. IgE
Rationale: IgG is the only antibody that crosses the placenta via neonatal Fc
receptors, providing passive immunity to the fetus. It is also the most abundant
immunoglobulin in serum.
106) ACTUAL EXAM 2026 COMPLETE EXAM
QUESTIONS AND CORRECT DETAILED
ANSWERS A NEW UPDATED VERSION LATEST
2026-2027 (100% CORRECT VERIFIED ANSWERS)
ALREADY GRADED A+
1. A 55-year-old man presents with chest pain radiating to the left arm. ECG
shows ST 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. Posterior descending artery
Rationale: ST elevation in leads II, III, and aVF indicates an inferior myocardial
infarction. The right coronary artery supplies the inferior wall of the left ventricle
in most individuals (right-dominant circulation). LAD occlusion affects anterior
leads (V1-V4), while circumflex occlusion typically affects lateral leads (I, aVL,
V5-V6).
2. A 23-year-old woman presents with fatigue, pallor, and microcytic anemia.
Which laboratory finding is most consistent with iron deficiency anemia?
A. Increased ferritin
B. Decreased total iron-binding capacity
C. Increased transferrin saturation
D. Decreased ferritin
,Rationale: Ferritin reflects total body iron stores. In iron deficiency anemia,
ferritin is decreased, TIBC is typically increased, and transferrin saturation is
decreased. Microcytic hypochromic anemia with low ferritin is diagnostic.
3. A 45-year-old man with chronic alcohol use presents with confusion, ataxia,
and ophthalmoplegia. Which vitamin deficiency is most likely responsible?
A. Vitamin B3 (Niacin)
B. Vitamin B1 (Thiamine)
C. Vitamin B6 (Pyridoxine)
D. Vitamin B12 (Cobalamin)
Rationale: The classic triad of confusion, ataxia, and ophthalmoplegia is Wernicke
encephalopathy, caused by thiamine (Vitamin B1) deficiency. This is commonly
seen in chronic alcohol use disorder due to poor nutrition and impaired thiamine
absorption.
4. A patient presents with chronic cough and hemoptysis. Imaging shows a
cavitary lesion in the upper lobe. What is the most likely diagnosis?
A. Klebsiella pneumoniae
B. Tuberculosis
C. Streptococcus pneumoniae
D. Lung abscess
Rationale: Mycobacterium tuberculosis infection classically presents with cavitary
lesions in the upper lobes, chronic cough, hemoptysis, and constitutional
symptoms. Upper lobe involvement is due to high oxygen tension favoring
mycobacterial growth.
5. Which vitamin deficiency is associated with a prolonged PT/INR?
A. Vitamin A
B. Vitamin C
,C. Vitamin K
D. Vitamin D
Rationale: Vitamin K is required for the gamma-carboxylation of clotting factors
II, VII, IX, and X. Deficiency leads to impaired coagulation, prolonging PT/INR.
Warfarin inhibits vitamin K epoxide reductase, producing the same effect.
6. A 28-year-old woman presents with heat intolerance, weight loss,
palpitations, and exophthalmos. Laboratory testing reveals suppressed TSH
and elevated T4. What is the most likely diagnosis?
A. Hashimoto thyroiditis
B. Subacute thyroiditis
C. Graves disease
D. Thyroid adenoma
Rationale: Graves disease is an autoimmune disorder caused by TSH receptor-
stimulating antibodies, leading to hyperthyroidism with suppressed TSH and
elevated T3/T4. Exophthalmos is a characteristic finding. Hashimoto thyroiditis
causes hypothyroidism.
7. A patient develops severe watery diarrhea after taking antibiotics. Which
organism is most likely responsible?
A. Escherichia coli
B. Salmonella enterica
C. Clostridioides difficile
D. Shigella dysenteriae
Rationale: C. difficile infection is the most common cause of antibiotic-associated
diarrhea and pseudomembranous colitis. Toxins A and B cause mucosal
inflammation and watery diarrhea. Risk factors include recent antibiotic use,
particularly clindamycin, cephalosporins, and fluoroquinolones.
, 8. A 65-year-old man presents with a resting tremor, bradykinesia, and
cogwheel rigidity. Which neurotransmitter deficiency is the primary
pathophysiology?
A. Acetylcholine
B. Dopamine
C. Serotonin
D. GABA
Rationale: Parkinson disease is characterized by degeneration of dopaminergic
neurons in the substantia nigra pars compacta, leading to decreased dopamine in
the striatum. This causes the classic triad of resting tremor, bradykinesia, and
rigidity.
9. A patient with severe dehydration has increased ADH secretion. What is the
mechanism of ADH action?
A. Increases sodium reabsorption in proximal tubule
B. Increases water reabsorption in collecting ducts via aquaporin-2 insertion
C. Decreases urea permeability in inner medulla
D. Stimulates aldosterone secretion
Rationale: ADH (vasopressin) increases water permeability of principal cells in
the collecting ducts by promoting insertion of aquaporin-2 channels into the
luminal membrane. This allows water reabsorption and urine concentration.
10. Which immunoglobulin class crosses the placenta?
A. IgA
B. IgG
C. IgM
D. IgE
Rationale: IgG is the only antibody that crosses the placenta via neonatal Fc
receptors, providing passive immunity to the fetus. It is also the most abundant
immunoglobulin in serum.
