Comprehensive Osteopathic Medical
Licensing Examination of the United
States (COMLEX-USA) Level 3 Practice
Exam: 100 Questions with Answers and
Detailed Rationales
1. A 68-year-old man with septic shock remains hypotensive after receiving 30
mL/kg of crystalloid fluids. Which vasopressor should be initiated first?
A. Dopamine
B. Epinephrine
C. Norepinephrine
D. Vasopressin
Answer: C. Norepinephrine
Rationale: Norepinephrine is the recommended first-line vasopressor in septic
shock because it effectively increases mean arterial pressure with fewer
arrhythmias than dopamine. Vasopressin may be added later if needed.
2. A 55-year-old woman with diabetes develops crushing substernal chest
pain. ECG demonstrates ST-segment elevation in leads II, III, and aVF. The
most appropriate immediate treatment is:
A. Exercise stress testing
B. Emergent percutaneous coronary intervention (PCI)
,C. Outpatient cardiology referral
D. Holter monitoring
Answer: B. Emergent percutaneous coronary intervention (PCI)
Rationale: ST-elevation myocardial infarction requires immediate reperfusion
therapy. PCI within 90 minutes is preferred whenever available.
3. A hospitalized patient suddenly develops pleuritic chest pain, dyspnea, and
tachycardia after hip replacement surgery. What is the best initial
diagnostic test if the patient is hemodynamically stable?
A. Chest X-ray
B. Echocardiogram
C. CT pulmonary angiography
D. Lower-extremity ultrasound
Answer: C. CT pulmonary angiography
Rationale: CT pulmonary angiography is the diagnostic test of choice for stable
patients with suspected pulmonary embolism.
4. A patient with chronic kidney disease has potassium of 7.2 mEq/L and
peaked T waves on ECG. The first medication should be:
A. Sodium polystyrene
B. Furosemide
C. Intravenous calcium gluconate
D. Sodium bicarbonate
,Answer: C. Intravenous calcium gluconate
Rationale: Calcium gluconate immediately stabilizes cardiac membranes
without lowering serum potassium and is the first priority when ECG changes
are present.
5. A patient presents with fever, hypotension, warm extremities, and elevated
lactate. Which intervention should occur within the first hour?
A. MRI abdomen
B. Colonoscopy
C. Broad-spectrum intravenous antibiotics
D. Corticosteroids alone
Answer: C. Broad-spectrum intravenous antibiotics
Rationale: Prompt administration of broad-spectrum antibiotics significantly
reduces mortality in septic shock and should occur as early as possible after
cultures are obtained.
6. Which acid-base disorder is expected in salicylate toxicity?
A. Respiratory acidosis only
B. Metabolic alkalosis only
C. Mixed respiratory alkalosis and metabolic acidosis
D. Metabolic acidosis only
Answer: C. Mixed respiratory alkalosis and metabolic acidosis
Rationale: Salicylates stimulate the respiratory center, producing respiratory
alkalosis, followed by accumulation of organic acids causing metabolic acidosis.
, 7. A patient with atrial fibrillation becomes hypotensive with altered mental
status. Appropriate management is:
A. Oral metoprolol
B. Intravenous digoxin
C. Immediate synchronized cardioversion
D. Observation
Answer: C. Immediate synchronized cardioversion
Rationale: Hemodynamically unstable atrial fibrillation requires immediate
synchronized cardioversion regardless of duration.
8. Which finding most strongly suggests bacterial meningitis?
A. CSF glucose normal
B. CSF lymphocyte predominance
C. CSF neutrophilic pleocytosis with low glucose
D. Elevated CSF glucose
Answer: C. CSF neutrophilic pleocytosis with low glucose
Rationale: Typical bacterial meningitis causes neutrophilic predominance,
elevated protein, and decreased CSF glucose.
9. A patient with diabetic ketoacidosis has potassium of 3.1 mEq/L. What
should occur before insulin administration?
A. Sodium bicarbonate
Licensing Examination of the United
States (COMLEX-USA) Level 3 Practice
Exam: 100 Questions with Answers and
Detailed Rationales
1. A 68-year-old man with septic shock remains hypotensive after receiving 30
mL/kg of crystalloid fluids. Which vasopressor should be initiated first?
A. Dopamine
B. Epinephrine
C. Norepinephrine
D. Vasopressin
Answer: C. Norepinephrine
Rationale: Norepinephrine is the recommended first-line vasopressor in septic
shock because it effectively increases mean arterial pressure with fewer
arrhythmias than dopamine. Vasopressin may be added later if needed.
2. A 55-year-old woman with diabetes develops crushing substernal chest
pain. ECG demonstrates ST-segment elevation in leads II, III, and aVF. The
most appropriate immediate treatment is:
A. Exercise stress testing
B. Emergent percutaneous coronary intervention (PCI)
,C. Outpatient cardiology referral
D. Holter monitoring
Answer: B. Emergent percutaneous coronary intervention (PCI)
Rationale: ST-elevation myocardial infarction requires immediate reperfusion
therapy. PCI within 90 minutes is preferred whenever available.
3. A hospitalized patient suddenly develops pleuritic chest pain, dyspnea, and
tachycardia after hip replacement surgery. What is the best initial
diagnostic test if the patient is hemodynamically stable?
A. Chest X-ray
B. Echocardiogram
C. CT pulmonary angiography
D. Lower-extremity ultrasound
Answer: C. CT pulmonary angiography
Rationale: CT pulmonary angiography is the diagnostic test of choice for stable
patients with suspected pulmonary embolism.
4. A patient with chronic kidney disease has potassium of 7.2 mEq/L and
peaked T waves on ECG. The first medication should be:
A. Sodium polystyrene
B. Furosemide
C. Intravenous calcium gluconate
D. Sodium bicarbonate
,Answer: C. Intravenous calcium gluconate
Rationale: Calcium gluconate immediately stabilizes cardiac membranes
without lowering serum potassium and is the first priority when ECG changes
are present.
5. A patient presents with fever, hypotension, warm extremities, and elevated
lactate. Which intervention should occur within the first hour?
A. MRI abdomen
B. Colonoscopy
C. Broad-spectrum intravenous antibiotics
D. Corticosteroids alone
Answer: C. Broad-spectrum intravenous antibiotics
Rationale: Prompt administration of broad-spectrum antibiotics significantly
reduces mortality in septic shock and should occur as early as possible after
cultures are obtained.
6. Which acid-base disorder is expected in salicylate toxicity?
A. Respiratory acidosis only
B. Metabolic alkalosis only
C. Mixed respiratory alkalosis and metabolic acidosis
D. Metabolic acidosis only
Answer: C. Mixed respiratory alkalosis and metabolic acidosis
Rationale: Salicylates stimulate the respiratory center, producing respiratory
alkalosis, followed by accumulation of organic acids causing metabolic acidosis.
, 7. A patient with atrial fibrillation becomes hypotensive with altered mental
status. Appropriate management is:
A. Oral metoprolol
B. Intravenous digoxin
C. Immediate synchronized cardioversion
D. Observation
Answer: C. Immediate synchronized cardioversion
Rationale: Hemodynamically unstable atrial fibrillation requires immediate
synchronized cardioversion regardless of duration.
8. Which finding most strongly suggests bacterial meningitis?
A. CSF glucose normal
B. CSF lymphocyte predominance
C. CSF neutrophilic pleocytosis with low glucose
D. Elevated CSF glucose
Answer: C. CSF neutrophilic pleocytosis with low glucose
Rationale: Typical bacterial meningitis causes neutrophilic predominance,
elevated protein, and decreased CSF glucose.
9. A patient with diabetic ketoacidosis has potassium of 3.1 mEq/L. What
should occur before insulin administration?
A. Sodium bicarbonate
