NEWEST VERSION 2026 COMLEX-USA PRACTICE EXAM
QUESTIONS WITH 100% VERIFIED ANSWERS PLUS
RATIONALE.
1. A 55-year-old man presents with chest pain radiating to the left arm. Which
biomarker rises earliest in myocardial infarction?
A. Troponin I
B. CK-MB
C. Myoglobin
D. LDH
Correct Answer: C
Rationale: Myoglobin rises within 1–2 hours, making it the earliest marker, though it
lacks specificity. Troponins are more specific but rise later. CK-MB rises after
myoglobin, and LDH is a late marker.
2. Which osteopathic technique is best suited for treating acute somatic dysfunction with
significant pain?
A. High-velocity low-amplitude (HVLA)
B. Muscle energy
C. Counterstrain
D. Myofascial release
Correct Answer: C
Rationale: Counterstrain is a gentle, indirect technique ideal for acute, painful
conditions. HVLA is contraindicated in acute pain states, while muscle energy and
myofascial release may be less comfortable.
3. A patient presents with hypercalcemia. Which condition is most likely associated?
A. Hypoparathyroidism
B. Vitamin D deficiency
C. Hyperparathyroidism
D. Chronic kidney disease
Correct Answer: C
Rationale: Hyperparathyroidism increases calcium levels via bone resorption and
renal reabsorption. The other conditions typically cause hypocalcemia.
4. A 30-year-old woman has exophthalmos and heat intolerance. What is the most likely
diagnosis?
A. Hashimoto thyroiditis
B. Graves disease
C. Subacute thyroiditis
D. Thyroid cancer
Correct Answer: B
, Rationale: Graves disease causes hyperthyroidism with exophthalmos due to
autoimmune stimulation. Other options do not present with these hallmark signs.
5. Which nerve is affected in carpal tunnel syndrome?
A. Ulnar nerve
B. Radial nerve
C. Median nerve
D. Axillary nerve
Correct Answer: C
Rationale: The median nerve passes through the carpal tunnel and is compressed in
this syndrome, causing sensory and motor deficits in its distribution.
6. A deficiency in which vitamin causes scurvy?
A. Vitamin A
B. Vitamin B12
C. Vitamin C
D. Vitamin D
Correct Answer: C
Rationale: Vitamin C deficiency leads to impaired collagen synthesis, causing scurvy.
Other vitamins are associated with different deficiencies.
7. Which electrolyte imbalance is most likely to cause peaked T waves on ECG?
A. Hypokalemia
B. Hyperkalemia
C. Hyponatremia
D. Hypercalcemia
Correct Answer: B
Rationale: Hyperkalemia causes characteristic peaked T waves. Hypokalemia causes
flattened T waves and U waves.
8. A patient presents with right lower quadrant pain and rebound tenderness. What is the
most likely diagnosis?
A. Cholecystitis
B. Pancreatitis
C. Appendicitis
D. Diverticulitis
Correct Answer: C
Rationale: Appendicitis typically presents with RLQ pain and rebound tenderness.
Other conditions present with different pain locations.
,9. Which hormone is responsible for milk ejection during breastfeeding?
A. Prolactin
B. Oxytocin
C. Estrogen
D. Progesterone
Correct Answer: B
Rationale: Oxytocin causes milk ejection, while prolactin is responsible for milk
production.
10. A “thumb sign” on lateral neck X-ray suggests which condition?
A. Croup
B. Epiglottitis
C. Asthma
D. Bronchitis
Correct Answer: B
Rationale: The thumb sign indicates a swollen epiglottis, characteristic of epiglottitis.
11. Which cranial nerve controls lateral eye movement?
A. CN III
B. CN IV
C. CN VI
D. CN V
Correct Answer: C
Rationale: CN VI (abducens nerve) innervates the lateral rectus muscle, responsible
for lateral eye movement.
12. A patient with diabetes has microalbuminuria. What is the best initial treatment?
A. Insulin
B. ACE inhibitors
C. Beta-blockers
D. Diuretics
Correct Answer: B
Rationale: ACE inhibitors reduce intraglomerular pressure and slow progression of
diabetic nephropathy.
13. Which condition is associated with “café-au-lait” spots?
A. Tuberous sclerosis
B. Neurofibromatosis type 1
C. Sturge-Weber syndrome
D. Marfan syndrome
Correct Answer: B
Rationale: NF1 presents with café-au-lait spots and neurofibromas.
, 14. Which artery is most commonly occluded in myocardial infarction?
A. Right coronary artery
B. Left circumflex artery
C. Left anterior descending artery
D. Posterior descending artery
Correct Answer: C
Rationale: The LAD is most commonly involved and supplies a large portion of the
myocardium.
15. A patient presents with “moon face” and truncal obesity. What is the likely diagnosis?
A. Addison disease
B. Cushing syndrome
C. Hypothyroidism
D. Hyperthyroidism
Correct Answer: B
Rationale: Cushing syndrome is characterized by excess cortisol leading to these
features.
16. Which type of hypersensitivity reaction is mediated by IgE?
A. Type I
B. Type II
C. Type III
D. Type IV
Correct Answer: A
Rationale: Type I hypersensitivity reactions are IgE-mediated and include allergies
and anaphylaxis.
17. A patient presents with severe headache and neck stiffness. What is the most likely
diagnosis?
A. Migraine
B. Meningitis
C. Tension headache
D. Cluster headache
Correct Answer: B
Rationale: Neck stiffness and headache are classic signs of meningitis.
18. Which bacteria is most commonly associated with peptic ulcers?
A. E. coli
B. H. pylori
C. Staphylococcus aureus
QUESTIONS WITH 100% VERIFIED ANSWERS PLUS
RATIONALE.
1. A 55-year-old man presents with chest pain radiating to the left arm. Which
biomarker rises earliest in myocardial infarction?
A. Troponin I
B. CK-MB
C. Myoglobin
D. LDH
Correct Answer: C
Rationale: Myoglobin rises within 1–2 hours, making it the earliest marker, though it
lacks specificity. Troponins are more specific but rise later. CK-MB rises after
myoglobin, and LDH is a late marker.
2. Which osteopathic technique is best suited for treating acute somatic dysfunction with
significant pain?
A. High-velocity low-amplitude (HVLA)
B. Muscle energy
C. Counterstrain
D. Myofascial release
Correct Answer: C
Rationale: Counterstrain is a gentle, indirect technique ideal for acute, painful
conditions. HVLA is contraindicated in acute pain states, while muscle energy and
myofascial release may be less comfortable.
3. A patient presents with hypercalcemia. Which condition is most likely associated?
A. Hypoparathyroidism
B. Vitamin D deficiency
C. Hyperparathyroidism
D. Chronic kidney disease
Correct Answer: C
Rationale: Hyperparathyroidism increases calcium levels via bone resorption and
renal reabsorption. The other conditions typically cause hypocalcemia.
4. A 30-year-old woman has exophthalmos and heat intolerance. What is the most likely
diagnosis?
A. Hashimoto thyroiditis
B. Graves disease
C. Subacute thyroiditis
D. Thyroid cancer
Correct Answer: B
, Rationale: Graves disease causes hyperthyroidism with exophthalmos due to
autoimmune stimulation. Other options do not present with these hallmark signs.
5. Which nerve is affected in carpal tunnel syndrome?
A. Ulnar nerve
B. Radial nerve
C. Median nerve
D. Axillary nerve
Correct Answer: C
Rationale: The median nerve passes through the carpal tunnel and is compressed in
this syndrome, causing sensory and motor deficits in its distribution.
6. A deficiency in which vitamin causes scurvy?
A. Vitamin A
B. Vitamin B12
C. Vitamin C
D. Vitamin D
Correct Answer: C
Rationale: Vitamin C deficiency leads to impaired collagen synthesis, causing scurvy.
Other vitamins are associated with different deficiencies.
7. Which electrolyte imbalance is most likely to cause peaked T waves on ECG?
A. Hypokalemia
B. Hyperkalemia
C. Hyponatremia
D. Hypercalcemia
Correct Answer: B
Rationale: Hyperkalemia causes characteristic peaked T waves. Hypokalemia causes
flattened T waves and U waves.
8. A patient presents with right lower quadrant pain and rebound tenderness. What is the
most likely diagnosis?
A. Cholecystitis
B. Pancreatitis
C. Appendicitis
D. Diverticulitis
Correct Answer: C
Rationale: Appendicitis typically presents with RLQ pain and rebound tenderness.
Other conditions present with different pain locations.
,9. Which hormone is responsible for milk ejection during breastfeeding?
A. Prolactin
B. Oxytocin
C. Estrogen
D. Progesterone
Correct Answer: B
Rationale: Oxytocin causes milk ejection, while prolactin is responsible for milk
production.
10. A “thumb sign” on lateral neck X-ray suggests which condition?
A. Croup
B. Epiglottitis
C. Asthma
D. Bronchitis
Correct Answer: B
Rationale: The thumb sign indicates a swollen epiglottis, characteristic of epiglottitis.
11. Which cranial nerve controls lateral eye movement?
A. CN III
B. CN IV
C. CN VI
D. CN V
Correct Answer: C
Rationale: CN VI (abducens nerve) innervates the lateral rectus muscle, responsible
for lateral eye movement.
12. A patient with diabetes has microalbuminuria. What is the best initial treatment?
A. Insulin
B. ACE inhibitors
C. Beta-blockers
D. Diuretics
Correct Answer: B
Rationale: ACE inhibitors reduce intraglomerular pressure and slow progression of
diabetic nephropathy.
13. Which condition is associated with “café-au-lait” spots?
A. Tuberous sclerosis
B. Neurofibromatosis type 1
C. Sturge-Weber syndrome
D. Marfan syndrome
Correct Answer: B
Rationale: NF1 presents with café-au-lait spots and neurofibromas.
, 14. Which artery is most commonly occluded in myocardial infarction?
A. Right coronary artery
B. Left circumflex artery
C. Left anterior descending artery
D. Posterior descending artery
Correct Answer: C
Rationale: The LAD is most commonly involved and supplies a large portion of the
myocardium.
15. A patient presents with “moon face” and truncal obesity. What is the likely diagnosis?
A. Addison disease
B. Cushing syndrome
C. Hypothyroidism
D. Hyperthyroidism
Correct Answer: B
Rationale: Cushing syndrome is characterized by excess cortisol leading to these
features.
16. Which type of hypersensitivity reaction is mediated by IgE?
A. Type I
B. Type II
C. Type III
D. Type IV
Correct Answer: A
Rationale: Type I hypersensitivity reactions are IgE-mediated and include allergies
and anaphylaxis.
17. A patient presents with severe headache and neck stiffness. What is the most likely
diagnosis?
A. Migraine
B. Meningitis
C. Tension headache
D. Cluster headache
Correct Answer: B
Rationale: Neck stiffness and headache are classic signs of meningitis.
18. Which bacteria is most commonly associated with peptic ulcers?
A. E. coli
B. H. pylori
C. Staphylococcus aureus
