COMLEX-USA Level 3 — Practice Exam
Practice Questions And Correct Answers
(Verified Answers) Plus Rationales 2027
Q&A | Instant Download Pdf
1. A 67-year-old man with hypertension and osteoarthritis presents with
increasing bilateral lower-extremity edema. He takes amlodipine,
lisinopril, and naproxen daily. Blood pressure is 138/82 mm Hg. Serum
creatinine has increased from 1.0 to 1.5 mg/dL over 3 months. Which
medication is the most likely contributor to his renal dysfunction?
A. Amlodipine
B. Lisinopril
C. Naproxen
D. Acetaminophen
E. Hydrochlorothiazide
Answer: C. Naproxen
,Rationale: NSAIDs inhibit cyclooxygenase-mediated prostaglandin
synthesis, causing afferent arteriolar vasoconstriction and reduced renal
perfusion. Chronic NSAID use can cause acute kidney injury and chronic
interstitial nephritis. The combination of an NSAID, ACE inhibitor, and
diuretic is particularly nephrotoxic.
2. A 72-year-old woman presents with sudden-onset aphasia and right-
sided weakness that began 90 minutes ago. CT of the head shows no
hemorrhage. Blood glucose is normal. Which is the most appropriate
immediate treatment if there are no contraindications?
A. Aspirin only
B. Intravenous alteplase
C. Intravenous heparin
D. Warfarin
E. Clopidogrel
Answer: B. Intravenous alteplase
Rationale: This patient has an acute ischemic stroke within the standard
thrombolytic window and has no evidence of intracranial hemorrhage. IV
thrombolysis is indicated when eligibility criteria are satisfied. Mechanical
thrombectomy should also be considered when a qualifying large-vessel
occlusion is present.
, 3. A 29-year-old woman presents with fatigue, weight loss, heat
intolerance, tremor, and palpitations. Examination shows diffuse
thyroid enlargement and lid retraction. TSH is suppressed and free T4
is elevated. Which antibody is most characteristic of her condition?
A. Anti-thyroid peroxidase antibody
B. Anti-thyroglobulin antibody
C. Thyroid-stimulating immunoglobulin
D. Anti-centromere antibody
E. Anti-double-stranded DNA antibody
Answer: C. Thyroid-stimulating immunoglobulin
Rationale: Graves disease is caused by antibodies that stimulate the TSH
receptor. Thyroid-stimulating immunoglobulins produce diffuse thyroid
hyperfunction and may cause ophthalmopathy and pretibial myxedema.
4. A 45-year-old man has crushing substernal chest pain for 30 minutes.
ECG shows ST-segment elevations 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
E. Posterior descending artery only
, Answer: C. Right coronary artery
Rationale: Inferior-wall myocardial infarction produces ST elevations in
leads II, III, and aVF and is most commonly caused by right coronary artery
occlusion. Right ventricular involvement should be assessed because
preload-dependent patients may become hypotensive after nitrates.
5. A 58-year-old woman presents with fatigue and exertional dyspnea.
Laboratory studies show hemoglobin 9.2 g/dL, MCV 72 fL, low serum
ferritin, and elevated total iron-binding capacity. Which diagnosis is
most likely?
A. Anemia of chronic disease
B. Iron deficiency anemia
C. Sideroblastic anemia
D. Vitamin B12 deficiency
E. Hemolytic anemia
Answer: B. Iron deficiency anemia
Rationale: Iron deficiency causes microcytic anemia with low ferritin and
increased total iron-binding capacity. In an older adult, occult
gastrointestinal blood loss must be investigated as a potential cause.
Practice Questions And Correct Answers
(Verified Answers) Plus Rationales 2027
Q&A | Instant Download Pdf
1. A 67-year-old man with hypertension and osteoarthritis presents with
increasing bilateral lower-extremity edema. He takes amlodipine,
lisinopril, and naproxen daily. Blood pressure is 138/82 mm Hg. Serum
creatinine has increased from 1.0 to 1.5 mg/dL over 3 months. Which
medication is the most likely contributor to his renal dysfunction?
A. Amlodipine
B. Lisinopril
C. Naproxen
D. Acetaminophen
E. Hydrochlorothiazide
Answer: C. Naproxen
,Rationale: NSAIDs inhibit cyclooxygenase-mediated prostaglandin
synthesis, causing afferent arteriolar vasoconstriction and reduced renal
perfusion. Chronic NSAID use can cause acute kidney injury and chronic
interstitial nephritis. The combination of an NSAID, ACE inhibitor, and
diuretic is particularly nephrotoxic.
2. A 72-year-old woman presents with sudden-onset aphasia and right-
sided weakness that began 90 minutes ago. CT of the head shows no
hemorrhage. Blood glucose is normal. Which is the most appropriate
immediate treatment if there are no contraindications?
A. Aspirin only
B. Intravenous alteplase
C. Intravenous heparin
D. Warfarin
E. Clopidogrel
Answer: B. Intravenous alteplase
Rationale: This patient has an acute ischemic stroke within the standard
thrombolytic window and has no evidence of intracranial hemorrhage. IV
thrombolysis is indicated when eligibility criteria are satisfied. Mechanical
thrombectomy should also be considered when a qualifying large-vessel
occlusion is present.
, 3. A 29-year-old woman presents with fatigue, weight loss, heat
intolerance, tremor, and palpitations. Examination shows diffuse
thyroid enlargement and lid retraction. TSH is suppressed and free T4
is elevated. Which antibody is most characteristic of her condition?
A. Anti-thyroid peroxidase antibody
B. Anti-thyroglobulin antibody
C. Thyroid-stimulating immunoglobulin
D. Anti-centromere antibody
E. Anti-double-stranded DNA antibody
Answer: C. Thyroid-stimulating immunoglobulin
Rationale: Graves disease is caused by antibodies that stimulate the TSH
receptor. Thyroid-stimulating immunoglobulins produce diffuse thyroid
hyperfunction and may cause ophthalmopathy and pretibial myxedema.
4. A 45-year-old man has crushing substernal chest pain for 30 minutes.
ECG shows ST-segment elevations 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
E. Posterior descending artery only
, Answer: C. Right coronary artery
Rationale: Inferior-wall myocardial infarction produces ST elevations in
leads II, III, and aVF and is most commonly caused by right coronary artery
occlusion. Right ventricular involvement should be assessed because
preload-dependent patients may become hypotensive after nitrates.
5. A 58-year-old woman presents with fatigue and exertional dyspnea.
Laboratory studies show hemoglobin 9.2 g/dL, MCV 72 fL, low serum
ferritin, and elevated total iron-binding capacity. Which diagnosis is
most likely?
A. Anemia of chronic disease
B. Iron deficiency anemia
C. Sideroblastic anemia
D. Vitamin B12 deficiency
E. Hemolytic anemia
Answer: B. Iron deficiency anemia
Rationale: Iron deficiency causes microcytic anemia with low ferritin and
increased total iron-binding capacity. In an older adult, occult
gastrointestinal blood loss must be investigated as a potential cause.
