COMSAE Phase 1 Form 115 Practice Exam – 130 High-
Yield USMLE/COMLEX Style MCQs with Detailed
Answers and Full Explanations for Medical Students |
instant pdf download
Question 1
A patient develops primary adrenal insufficiency due to autoimmune destruction of the
adrenal cortex, resulting in decreased cortisol and aldosterone production.
Which of the following changes is most directly responsible for the development of
hyperkalemia in this condition?
A. Decreased ACTH secretion
B. Decreased sodium reabsorption in the distal nephron
C. Increased renin secretion
D. Increased glucose utilization
Answer: B
Rationale: Aldosterone normally promotes sodium reabsorption and potassium excretion in
the distal nephron. In Addison disease, low aldosterone leads to decreased sodium
reabsorption and decreased potassium excretion → hyperkalemia.
Question 2
A patient presents with hyperthyroidism due to Graves disease.
Which of the following best explains the pathophysiology of this condition?
A. Destruction of thyroid follicles by cytotoxic T cells
B. Antibody-mediated stimulation of TSH receptors
C. Decreased iodine uptake in the thyroid gland
D. Autonomous thyroid hormone secretion independent of TSH receptors
Answer: B
Rationale: Graves disease is caused by thyroid-stimulating immunoglobulins that bind and
activate TSH receptors, increasing T3/T4 production.
,Question 3
A patient with uncontrolled diabetes mellitus develops diabetic ketoacidosis (DKA).
Which metabolic pathway is primarily responsible for the generation of ketone bodies?
A. Glycolysis
B. Glycogenolysis
C. Fatty acid β-oxidation
D. Pentose phosphate pathway
Answer: C
Rationale: In insulin deficiency, lipolysis increases → free fatty acids undergo β-oxidation in
the liver → ketone body production.
Question 4
A patient presents with hypertension, hypokalemia, and metabolic alkalosis due to
excess aldosterone secretion.
Which segment of the nephron is primarily affected?
A. Proximal tubule
B. Loop of Henle
C. Distal tubule and collecting duct
D. Glomerulus
Answer: C
Rationale: Aldosterone acts on the distal tubule and collecting duct to increase sodium
reabsorption and potassium/hydrogen excretion
Question 5
A patient presents with progressive muscle weakness that worsens with activity and
improves with rest due to autoimmune destruction of postsynaptic receptors.
Which receptor is targeted?
A. Dopamine receptor
B. Acetylcholine receptor
,C. GABA receptor
D. Serotonin receptor
Answer: B
Rationale: Myasthenia gravis is caused by antibodies against postsynaptic acetylcholine
receptors.
Question 6
A patient presents with acute myocardial infarction.
Which of the following cellular changes occurs first after ischemia?
A. Coagulative necrosis
B. Neutrophil infiltration
C. Decreased ATP production
D. Fibrosis
Answer: C
Rationale: Ischemia leads to rapid ATP depletion within minutes, preceding structural
damage.
Question 7
A patient presents with watery diarrhea caused by increased cAMP levels in intestinal
epithelial cells.
Which organism is most likely responsible?
A. Salmonella
B. Shigella
C. Vibrio cholerae
D. Clostridioides difficile
Answer: C
Rationale: Cholera toxin increases cAMP, causing massive secretion of water into the
intestines.
Question 8
, A patient presents with microcytic anemia characterized by low ferritin and high TIBC.
Which condition is most likely?
A. Anemia of chronic disease
B. Iron deficiency anemia
C. Vitamin B12 deficiency
D. Aplastic anemia
Answer: B
Rationale: Iron deficiency anemia presents with low ferritin (iron stores) and high TIBC.
Question 9
A patient presents with sudden severe headache due to subarachnoid hemorrhage.
What is the most common underlying cause?
A. Hypertensive hemorrhage
B. Ruptured berry aneurysm
C. Arteriovenous malformation
D. Trauma
Answer: B
Rationale: Most subarachnoid hemorrhages are due to rupture of berry aneurysms.
Question 10
A patient presents with hypocalcemia and tetany.
Which hormone deficiency is most likely responsible?
A. Calcitonin
B. Parathyroid hormone
C. Vitamin D
D. Cortisol
Answer: B
Rationale: PTH deficiency leads to decreased calcium levels and tetany.
Yield USMLE/COMLEX Style MCQs with Detailed
Answers and Full Explanations for Medical Students |
instant pdf download
Question 1
A patient develops primary adrenal insufficiency due to autoimmune destruction of the
adrenal cortex, resulting in decreased cortisol and aldosterone production.
Which of the following changes is most directly responsible for the development of
hyperkalemia in this condition?
A. Decreased ACTH secretion
B. Decreased sodium reabsorption in the distal nephron
C. Increased renin secretion
D. Increased glucose utilization
Answer: B
Rationale: Aldosterone normally promotes sodium reabsorption and potassium excretion in
the distal nephron. In Addison disease, low aldosterone leads to decreased sodium
reabsorption and decreased potassium excretion → hyperkalemia.
Question 2
A patient presents with hyperthyroidism due to Graves disease.
Which of the following best explains the pathophysiology of this condition?
A. Destruction of thyroid follicles by cytotoxic T cells
B. Antibody-mediated stimulation of TSH receptors
C. Decreased iodine uptake in the thyroid gland
D. Autonomous thyroid hormone secretion independent of TSH receptors
Answer: B
Rationale: Graves disease is caused by thyroid-stimulating immunoglobulins that bind and
activate TSH receptors, increasing T3/T4 production.
,Question 3
A patient with uncontrolled diabetes mellitus develops diabetic ketoacidosis (DKA).
Which metabolic pathway is primarily responsible for the generation of ketone bodies?
A. Glycolysis
B. Glycogenolysis
C. Fatty acid β-oxidation
D. Pentose phosphate pathway
Answer: C
Rationale: In insulin deficiency, lipolysis increases → free fatty acids undergo β-oxidation in
the liver → ketone body production.
Question 4
A patient presents with hypertension, hypokalemia, and metabolic alkalosis due to
excess aldosterone secretion.
Which segment of the nephron is primarily affected?
A. Proximal tubule
B. Loop of Henle
C. Distal tubule and collecting duct
D. Glomerulus
Answer: C
Rationale: Aldosterone acts on the distal tubule and collecting duct to increase sodium
reabsorption and potassium/hydrogen excretion
Question 5
A patient presents with progressive muscle weakness that worsens with activity and
improves with rest due to autoimmune destruction of postsynaptic receptors.
Which receptor is targeted?
A. Dopamine receptor
B. Acetylcholine receptor
,C. GABA receptor
D. Serotonin receptor
Answer: B
Rationale: Myasthenia gravis is caused by antibodies against postsynaptic acetylcholine
receptors.
Question 6
A patient presents with acute myocardial infarction.
Which of the following cellular changes occurs first after ischemia?
A. Coagulative necrosis
B. Neutrophil infiltration
C. Decreased ATP production
D. Fibrosis
Answer: C
Rationale: Ischemia leads to rapid ATP depletion within minutes, preceding structural
damage.
Question 7
A patient presents with watery diarrhea caused by increased cAMP levels in intestinal
epithelial cells.
Which organism is most likely responsible?
A. Salmonella
B. Shigella
C. Vibrio cholerae
D. Clostridioides difficile
Answer: C
Rationale: Cholera toxin increases cAMP, causing massive secretion of water into the
intestines.
Question 8
, A patient presents with microcytic anemia characterized by low ferritin and high TIBC.
Which condition is most likely?
A. Anemia of chronic disease
B. Iron deficiency anemia
C. Vitamin B12 deficiency
D. Aplastic anemia
Answer: B
Rationale: Iron deficiency anemia presents with low ferritin (iron stores) and high TIBC.
Question 9
A patient presents with sudden severe headache due to subarachnoid hemorrhage.
What is the most common underlying cause?
A. Hypertensive hemorrhage
B. Ruptured berry aneurysm
C. Arteriovenous malformation
D. Trauma
Answer: B
Rationale: Most subarachnoid hemorrhages are due to rupture of berry aneurysms.
Question 10
A patient presents with hypocalcemia and tetany.
Which hormone deficiency is most likely responsible?
A. Calcitonin
B. Parathyroid hormone
C. Vitamin D
D. Cortisol
Answer: B
Rationale: PTH deficiency leads to decreased calcium levels and tetany.
