COMSAE Form 110 – Complete Exam 2026: 200
Practice Questions with Verified Answers &
Rationales – COMLEX-USA Level 1 Prep | Instant
Pdf Download
Questions 1–30: Basic Sciences (Anatomy, Physiology, Biochemistry, Pathology,
Micro, Pharm)
1. A 22-year-old man has weakness in wrist extension and decreased sensation over
the dorsal hand after a mid-shaft humerus fracture. Which nerve is most likely
injured?
A. Median nerve
B. Ulnar nerve
C. Radial nerve
D. Axillary nerve
Mid-shaft humeral fractures commonly injure the radial nerve, causing wrist drop and dorsal
hand sensory loss.
2. A 45-year-old woman with fatigue, weight gain, cold intolerance, and delayed reflex
relaxation most likely has abnormal levels of which hormone?
A. Cortisol
B. Thyroxine (T4)
C. Parathyroid hormone
D. Aldosterone
These are classic hypothyroidism symptoms; T4 (and T3) would be low, TSH high.
3. Which enzyme deficiency causes phenylketonuria (PKU)?
,A. Phenylalanine hydroxylase
B. Tyrosinase
C. Branched-chain α-ketoacid dehydrogenase
D. Glucose-6-phosphatase
PKU is due to phenylalanine hydroxylase deficiency, leading to elevated phenylalanine.
4. A 60-year-old man with chronic alcohol use presents with confusion, ataxia, and
ophthalmoplegia. Which vitamin deficiency is most likely?
A. Vitamin B12
B. Thiamine (B1)
C. Folate
D. Niacin
This triad describes Wernicke encephalopathy from thiamine deficiency.
5. Which of the following is the most common cause of community-acquired
pneumonia?
A. Staphylococcus aureus
B. Mycoplasma pneumoniae
C. Streptococcus pneumoniae
D. Klebsiella pneumoniae
S. pneumoniae remains the leading cause of typical community-acquired pneumonia.
6. A 30-year-old woman has a malar rash, photosensitivity, oral ulcers, and positive
anti-dsDNA. Which diagnosis is most likely?
A. Dermatomyositis
B. Systemic lupus erythematosus (SLE)
C. Sjögren syndrome
D. Mixed connective tissue disease
The clinical features and anti-dsDNA positivity are classic for SLE.
,7. Which drug class is first-line for treatment of an acute gout flare in a patient
without contraindications?
A. Allopurinol
B. NSAIDs
C. Colchicine only
D. Probenecid
NSAIDs are first-line for acute gout flares; allopurinol is for long-term urate lowering.
8. A 55-year-old man with type 2 diabetes has microalbuminuria. Which medication
provides renal protection beyond glucose control?
A. Metformin
B. Sulfonylurea
C. ACE inhibitor
D. Thiazolidinedione
ACE inhibitors (or ARBs) reduce intraglomerular pressure and slow diabetic nephropathy
progression.
9. Which of the following is the most common type of skin cancer?
A. Melanoma
B. Squamous cell carcinoma
C. Basal cell carcinoma
D. Merkel cell carcinoma
Basal cell carcinoma is the most common skin cancer, with low metastatic potential.
10. A 25-year-old man has a painless testicular mass. Ultrasound shows a solid
intratesticular lesion. Which tumor marker is most likely elevated in a
non-seminomatous germ cell tumor?
A. PSA
B. β-hCG and/or AFP
C. CA-125
D. CEA
, Non-seminomatous germ cell tumors often elevate β-hCG and/or AFP; seminomas may
elevate β-hCG only.
11. Which of the following best describes the mechanism of action of warfarin?
A. Direct thrombin inhibitor
B. Inhibits vitamin K–dependent clotting factors (II, VII, IX, X)
C. Platelet ADP receptor antagonist
D. Fibrinolytic agent
Warfarin inhibits vitamin K epoxide reductase, reducing activation of II, VII, IX, X.
12. A 70-year-old man has resting tremor, rigidity, bradykinesia, and postural
instability. Which neurotransmitter is primarily decreased in this condition?
A. Serotonin
B. Dopamine
C. GABA
D. Acetylcholine
These are classic Parkinson disease features due to dopaminergic neuron loss in the
substantia nigra.
13. Which of the following is the most common cause of iron deficiency anemia in an
adult male in a developed country?
A. Dietary insufficiency alone
B. Chronic gastrointestinal blood loss
C. Hemolysis
D. Bone marrow failure
In adult men, GI blood loss (e.g., ulcers, malignancy) is the most concerning cause of iron
deficiency.
14. A newborn has projectile non-bilious vomiting and a palpable “olive” mass in the
epigastrium. Which diagnosis is most likely?
Practice Questions with Verified Answers &
Rationales – COMLEX-USA Level 1 Prep | Instant
Pdf Download
Questions 1–30: Basic Sciences (Anatomy, Physiology, Biochemistry, Pathology,
Micro, Pharm)
1. A 22-year-old man has weakness in wrist extension and decreased sensation over
the dorsal hand after a mid-shaft humerus fracture. Which nerve is most likely
injured?
A. Median nerve
B. Ulnar nerve
C. Radial nerve
D. Axillary nerve
Mid-shaft humeral fractures commonly injure the radial nerve, causing wrist drop and dorsal
hand sensory loss.
2. A 45-year-old woman with fatigue, weight gain, cold intolerance, and delayed reflex
relaxation most likely has abnormal levels of which hormone?
A. Cortisol
B. Thyroxine (T4)
C. Parathyroid hormone
D. Aldosterone
These are classic hypothyroidism symptoms; T4 (and T3) would be low, TSH high.
3. Which enzyme deficiency causes phenylketonuria (PKU)?
,A. Phenylalanine hydroxylase
B. Tyrosinase
C. Branched-chain α-ketoacid dehydrogenase
D. Glucose-6-phosphatase
PKU is due to phenylalanine hydroxylase deficiency, leading to elevated phenylalanine.
4. A 60-year-old man with chronic alcohol use presents with confusion, ataxia, and
ophthalmoplegia. Which vitamin deficiency is most likely?
A. Vitamin B12
B. Thiamine (B1)
C. Folate
D. Niacin
This triad describes Wernicke encephalopathy from thiamine deficiency.
5. Which of the following is the most common cause of community-acquired
pneumonia?
A. Staphylococcus aureus
B. Mycoplasma pneumoniae
C. Streptococcus pneumoniae
D. Klebsiella pneumoniae
S. pneumoniae remains the leading cause of typical community-acquired pneumonia.
6. A 30-year-old woman has a malar rash, photosensitivity, oral ulcers, and positive
anti-dsDNA. Which diagnosis is most likely?
A. Dermatomyositis
B. Systemic lupus erythematosus (SLE)
C. Sjögren syndrome
D. Mixed connective tissue disease
The clinical features and anti-dsDNA positivity are classic for SLE.
,7. Which drug class is first-line for treatment of an acute gout flare in a patient
without contraindications?
A. Allopurinol
B. NSAIDs
C. Colchicine only
D. Probenecid
NSAIDs are first-line for acute gout flares; allopurinol is for long-term urate lowering.
8. A 55-year-old man with type 2 diabetes has microalbuminuria. Which medication
provides renal protection beyond glucose control?
A. Metformin
B. Sulfonylurea
C. ACE inhibitor
D. Thiazolidinedione
ACE inhibitors (or ARBs) reduce intraglomerular pressure and slow diabetic nephropathy
progression.
9. Which of the following is the most common type of skin cancer?
A. Melanoma
B. Squamous cell carcinoma
C. Basal cell carcinoma
D. Merkel cell carcinoma
Basal cell carcinoma is the most common skin cancer, with low metastatic potential.
10. A 25-year-old man has a painless testicular mass. Ultrasound shows a solid
intratesticular lesion. Which tumor marker is most likely elevated in a
non-seminomatous germ cell tumor?
A. PSA
B. β-hCG and/or AFP
C. CA-125
D. CEA
, Non-seminomatous germ cell tumors often elevate β-hCG and/or AFP; seminomas may
elevate β-hCG only.
11. Which of the following best describes the mechanism of action of warfarin?
A. Direct thrombin inhibitor
B. Inhibits vitamin K–dependent clotting factors (II, VII, IX, X)
C. Platelet ADP receptor antagonist
D. Fibrinolytic agent
Warfarin inhibits vitamin K epoxide reductase, reducing activation of II, VII, IX, X.
12. A 70-year-old man has resting tremor, rigidity, bradykinesia, and postural
instability. Which neurotransmitter is primarily decreased in this condition?
A. Serotonin
B. Dopamine
C. GABA
D. Acetylcholine
These are classic Parkinson disease features due to dopaminergic neuron loss in the
substantia nigra.
13. Which of the following is the most common cause of iron deficiency anemia in an
adult male in a developed country?
A. Dietary insufficiency alone
B. Chronic gastrointestinal blood loss
C. Hemolysis
D. Bone marrow failure
In adult men, GI blood loss (e.g., ulcers, malignancy) is the most concerning cause of iron
deficiency.
14. A newborn has projectile non-bilious vomiting and a palpable “olive” mass in the
epigastrium. Which diagnosis is most likely?
