COMLEX-USA LEVEL 1 COMPREHENSIVE PRACTICE
EXAM: 200 HIGH-YIELD QUESTIONS WITH
DETAILED RATIONALES LATEST EDITION POCKET
CERTIFICATE EASLY A+ GRADED
1. A 24-year-old man presents with fatigue, dark urine, and jaundice two days after taking
trimethoprim-sulfamethoxazole for a urinary tract infection. He recently returned from a
malaria-endemic region but has otherwise been healthy. Physical examination reveals
scleral icterus. Laboratory studies show hemoglobin 8.7 g/dL, elevated lactate
dehydrogenase, decreased haptoglobin, and increased indirect bilirubin. A peripheral
blood smear demonstrates numerous "bite cells." Which of the following is the most
likely underlying cause of this patient's condition?
A. Deficiency of pyruvate kinase leading to ATP depletion in erythrocytes
B. Deficiency of glucose-6-phosphate dehydrogenase resulting in impaired NADPH production
C. Autoimmune destruction of erythrocytes mediated by warm IgG antibodies
D. Sceptrin mutation causing hereditary spherocytosis
E. Defective β-globin synthesis resulting in ineffective erythropoiesis
Answer: B. Deficiency of glucose-6-phosphate dehydrogenase resulting in impaired NADPH
production
Rationale: Glucose-6-phosphate dehydrogenase deficiency reduces NADPH production, limiting
regeneration of reduced glutathione. Oxidative stress from sulfonamides, infections, or certain
foods causes denaturation of hemoglobin into Heinz bodies, which splenic macrophages
remove, producing characteristic bite cells. Hemolysis leads to elevated LDH, indirect
hyperbilirubinemia, low haptoglobin, and dark urine.
2. A 67-year-old woman with long-standing hypertension develops progressive shortness of
breath and bilateral lower extremity edema. Echocardiography demonstrates concentric
left ventricular hypertrophy with a preserved ejection fraction. Which of the following
best explains the primary abnormality responsible for her symptoms?
A. Reduced ventricular compliance causing impaired diastolic filling
B. Impaired myocardial contractility resulting in decreased stroke volume
,C. Acute rupture of the papillary muscles
D. Left ventricular free wall rupture
E. Dilated cardiomyopathy due to chronic alcohol use
Answer: A. Reduced ventricular compliance causing impaired diastolic filling
Rationale: Chronic hypertension commonly produces concentric hypertrophy, leading to
decreased ventricular compliance and impaired relaxation during diastole. Patients develop
heart failure with preserved ejection fraction (HFpEF), characterized by pulmonary congestion
despite normal systolic function. *
3. A 7-year-old child develops fever, sore throat, and a diffuse sandpaper-like rash.
Examination reveals circumoral pallor and a strawberry tongue. Which organism is the
most likely cause?
A. Staphylococcus aureus
B. Streptococcus pyogenes
C. Corynebacterium diphtheriae
D. Haemophiles’ influenzae
E. Neisseria meningitidis
Answer: B. Streptococcus pyogenes
Rationale: Scarlet fever is caused by erythrogenic toxin-producing Group A Streptococcus.
Characteristic findings include pharyngitis, strawberry tongue, circumoral pallor, Pastia lines,
and a diffuse sandpaper rash.*
4. A researcher administers a drug that competitively inhibits angiotensin-converting
enzyme (ACE). Which physiological change is most likely to occur?
A. Increased angiotensin II production
B. Increased aldosterone secretion
C. Increased bradykinin concentration
D. Increased systemic vascular resistance
, E. Increased efferent arteriolar constriction
Answer: C. Increased bradykinin concentration
Rationale: ACE normally converts angiotensin I to angiotensin II while degrading bradykinin. ACE
inhibition decreases angiotensin II and aldosterone while increasing bradykinin, contributing to
cough and angioedema.*
5. A 45-year-old man presents with recurrent peptic ulcers refractory to proton pump
inhibitor therapy. His fasting serum gastrin level is markedly elevated. Which syndrome is
most likely present?
A. Zollinger-Ellison syndrome
B. MEN type 2
C. Carcinoid syndrome
D. VIPoma
E. Insulinoma
Answer: A. Zollinger-Ellison syndrome
Rationale: Gastrin-secreting tumors (gastrinomas) cause excessive gastric acid production,
resulting in multiple refractory ulcers and diarrhea. Gastrinomas are associated with MEN1.*
6. A patient undergoes osteopathic structural examination. The physician identifies tissue
texture abnormalities, asymmetry, restricted motion, and tenderness in the thoracic
spine. These findings are collectively referred to as:
A. Fryette principles
B. Chapman points
C. TART findings
D. Viscerosomatic reflexes
E. Counterstrain points
Answer: C. TART findings
EXAM: 200 HIGH-YIELD QUESTIONS WITH
DETAILED RATIONALES LATEST EDITION POCKET
CERTIFICATE EASLY A+ GRADED
1. A 24-year-old man presents with fatigue, dark urine, and jaundice two days after taking
trimethoprim-sulfamethoxazole for a urinary tract infection. He recently returned from a
malaria-endemic region but has otherwise been healthy. Physical examination reveals
scleral icterus. Laboratory studies show hemoglobin 8.7 g/dL, elevated lactate
dehydrogenase, decreased haptoglobin, and increased indirect bilirubin. A peripheral
blood smear demonstrates numerous "bite cells." Which of the following is the most
likely underlying cause of this patient's condition?
A. Deficiency of pyruvate kinase leading to ATP depletion in erythrocytes
B. Deficiency of glucose-6-phosphate dehydrogenase resulting in impaired NADPH production
C. Autoimmune destruction of erythrocytes mediated by warm IgG antibodies
D. Sceptrin mutation causing hereditary spherocytosis
E. Defective β-globin synthesis resulting in ineffective erythropoiesis
Answer: B. Deficiency of glucose-6-phosphate dehydrogenase resulting in impaired NADPH
production
Rationale: Glucose-6-phosphate dehydrogenase deficiency reduces NADPH production, limiting
regeneration of reduced glutathione. Oxidative stress from sulfonamides, infections, or certain
foods causes denaturation of hemoglobin into Heinz bodies, which splenic macrophages
remove, producing characteristic bite cells. Hemolysis leads to elevated LDH, indirect
hyperbilirubinemia, low haptoglobin, and dark urine.
2. A 67-year-old woman with long-standing hypertension develops progressive shortness of
breath and bilateral lower extremity edema. Echocardiography demonstrates concentric
left ventricular hypertrophy with a preserved ejection fraction. Which of the following
best explains the primary abnormality responsible for her symptoms?
A. Reduced ventricular compliance causing impaired diastolic filling
B. Impaired myocardial contractility resulting in decreased stroke volume
,C. Acute rupture of the papillary muscles
D. Left ventricular free wall rupture
E. Dilated cardiomyopathy due to chronic alcohol use
Answer: A. Reduced ventricular compliance causing impaired diastolic filling
Rationale: Chronic hypertension commonly produces concentric hypertrophy, leading to
decreased ventricular compliance and impaired relaxation during diastole. Patients develop
heart failure with preserved ejection fraction (HFpEF), characterized by pulmonary congestion
despite normal systolic function. *
3. A 7-year-old child develops fever, sore throat, and a diffuse sandpaper-like rash.
Examination reveals circumoral pallor and a strawberry tongue. Which organism is the
most likely cause?
A. Staphylococcus aureus
B. Streptococcus pyogenes
C. Corynebacterium diphtheriae
D. Haemophiles’ influenzae
E. Neisseria meningitidis
Answer: B. Streptococcus pyogenes
Rationale: Scarlet fever is caused by erythrogenic toxin-producing Group A Streptococcus.
Characteristic findings include pharyngitis, strawberry tongue, circumoral pallor, Pastia lines,
and a diffuse sandpaper rash.*
4. A researcher administers a drug that competitively inhibits angiotensin-converting
enzyme (ACE). Which physiological change is most likely to occur?
A. Increased angiotensin II production
B. Increased aldosterone secretion
C. Increased bradykinin concentration
D. Increased systemic vascular resistance
, E. Increased efferent arteriolar constriction
Answer: C. Increased bradykinin concentration
Rationale: ACE normally converts angiotensin I to angiotensin II while degrading bradykinin. ACE
inhibition decreases angiotensin II and aldosterone while increasing bradykinin, contributing to
cough and angioedema.*
5. A 45-year-old man presents with recurrent peptic ulcers refractory to proton pump
inhibitor therapy. His fasting serum gastrin level is markedly elevated. Which syndrome is
most likely present?
A. Zollinger-Ellison syndrome
B. MEN type 2
C. Carcinoid syndrome
D. VIPoma
E. Insulinoma
Answer: A. Zollinger-Ellison syndrome
Rationale: Gastrin-secreting tumors (gastrinomas) cause excessive gastric acid production,
resulting in multiple refractory ulcers and diarrhea. Gastrinomas are associated with MEN1.*
6. A patient undergoes osteopathic structural examination. The physician identifies tissue
texture abnormalities, asymmetry, restricted motion, and tenderness in the thoracic
spine. These findings are collectively referred to as:
A. Fryette principles
B. Chapman points
C. TART findings
D. Viscerosomatic reflexes
E. Counterstrain points
Answer: C. TART findings
