Comsae Phase 1 (Form 115) Practice
Examination Questions And Correct Answers
(Verified Answers) Plus Rationales
1. A 23-year-old man presents with fever, cough, and rusty sputum. Lung exam shows crackles in the
right lower lobe. Chest X-ray shows lobar consolidation. The most likely organism is:
A. Haemophilus influenzae
B. Mycoplasma pneumoniae
C. Streptococcus pneumoniae
D. Chlamydophila pneumoniae
Correct Answer: C. Streptococcus pneumoniae
Rationale: Streptococcus pneumoniae is the most common cause of community-acquired lobar
pneumonia. The classic presentation includes fever, cough, and "rusty" sputum, which is due to blood
from inflammation. Lobar consolidation on X-ray is a hallmark finding .
2. A 56-year-old woman presents with fatigue, cold intolerance, and weight gain. Lab results show a
markedly elevated TSH and low free T4. What is the most likely diagnosis?
A. Secondary hypothyroidism
B. Thyrotoxicosis
C. Primary hypothyroidism
D. Subclinical hyperthyroidism
Correct Answer: C. Primary hypothyroidism
Rationale: This pattern of elevated TSH with low free T4 is diagnostic of primary hypothyroidism. The
elevated TSH indicates that the thyroid gland itself is not producing enough hormone, and the pituitary
is trying to compensate by releasing more TSH .
3. A 68-year-old man with Parkinson's disease presents with bradykinesia, rigidity, and a resting
tremor. The underlying pathophysiology involves the loss of neurons in which area of the brain?
A. Loss of dopamine in the globus pallidus
B. Loss of serotonin in the substantia nigra
,C. Loss of dopamine from the substantia nigra pars compacta
D. Loss of norepinephrine from the locus coeruleus
Correct Answer: C. Loss of dopamine from the substantia nigra pars compacta
Rationale: Parkinson's disease is characterized by the progressive degeneration of dopaminergic
neurons in the substantia nigra pars compacta. This leads to a dopamine deficiency in the striatum,
causing the classic motor symptoms of bradykinesia, rigidity, and resting tremor .
4. A 45-year-old man presents with severe right-upper-quadrant pain that radiates to the right
shoulder. The pain began several hours after a large, fatty meal. On exam, he has a positive Murphy
sign. What is the most likely diagnosis?
A. Acute pancreatitis
B. Peptic ulcer disease
C. Acute cholecystitis
D. Acute appendicitis
Correct Answer: C. Acute cholecystitis
Rationale: The presentation of post-prandial (especially fatty meal) right upper quadrant pain with a
positive Murphy sign (inspiration halts during palpation of the RUQ) is classic for acute cholecystitis,
most commonly due to gallstones .
5. A 24-year-old man presents with dysuria and a purulent urethral discharge. A Gram stain of the
discharge reveals Gram-negative diplococci. What is the most appropriate treatment?
A. Oral erythromycin
B. Oral amoxicillin
C. Intramuscular ceftriaxone and oral doxycycline
D. Oral metronidazole
Correct Answer: C. Intramuscular ceftriaxone and oral doxycycline
Rationale: The presence of Gram-negative diplococci in a male with urethritis is indicative of Neisseria
gonorrhoeae. The standard of care is dual therapy with ceftriaxone (for gonorrhea) and doxycycline (to
cover for concurrent Chlamydia trachomatis infection, which is a common co-infection) .
6. A 20-year-old college student presents with severe fatigue, sore throat, and lymphadenopathy. A
peripheral blood smear shows atypical lymphocytes. What is the most likely causative virus?
A. Cytomegalovirus (CMV)
B. Adenovirus
,C. Epstein-Barr virus (EBV)
D. Herpes simplex virus-1 (HSV-1)
Correct Answer: C. Epstein-Barr virus (EBV)
Rationale: The triad of fever, pharyngitis, and lymphadenopathy, along with the presence of atypical
lymphocytes on a blood smear, is classic for infectious mononucleosis, which is caused by the Epstein-
Barr virus .
7. A 50-year-old man with a history of alcohol use disorder presents with epigastric pain radiating to
the back. Labs show elevated serum amylase and lipase. What is the initial management?
A. Immediate surgical consultation
B. NPO status and aggressive IV fluid resuscitation
C. Endoscopic retrograde cholangiopancreatography (ERCP)
D. Broad-spectrum antibiotics
Correct Answer: B. NPO status and aggressive IV fluid resuscitation
Rationale: The presentation is consistent with acute pancreatitis. Initial management is supportive, with
bowel rest (NPO) to reduce pancreatic stimulation and aggressive intravenous fluid resuscitation to
maintain intravascular volume and prevent pancreatic necrosis .
8. A 7-year-old child presents with a sore throat and a diffuse, erythematous, "sandpaper-like" rash
on the trunk. The tongue appears red and swollen, described as a "strawberry tongue." What is the
most likely cause?
A. Coxsackie virus
B. Adenovirus
C. Streptococcus pyogenes
D. Staphylococcus aureus
Correct Answer: C. Streptococcus pyogenes
Rationale: These are classic signs of scarlet fever, which is caused by group
A Streptococcus (Streptococcus pyogenes) that produces an erythrogenic toxin. The sandpaper rash and
strawberry tongue are hallmark features .
9. A 40-year-old man with a history of alcoholism presents with macrocytic anemia and paresthesias
in his lower extremities. Which vitamin deficiency is most likely?
A. Folate
B. Vitamin B2 (riboflavin)
, C. Vitamin B12 (cobalamin)
D. Vitamin C
Correct Answer: C. Vitamin B12 (cobalamin)
Rationale: While both folate and B12 deficiencies can cause macrocytic anemia, the presence of
neurologic deficits (paresthesias, subacute combined degeneration) points specifically to a vitamin B12
deficiency. Folate deficiency does not cause neurologic symptoms .
10. A patient with a history of atrial fibrillation is prescribed warfarin. The therapeutic effect of
warfarin is monitored by the International Normalized Ratio (INR) because it works by:
A. Activating vitamin K
B. Inhibiting vitamin K epoxide reductase
C. Directly blocking thrombin
D. Activating protein C
Correct Answer: B. Inhibiting vitamin K epoxide reductase
Rationale: Warfarin is a vitamin K antagonist. It inhibits the enzyme vitamin K epoxide reductase, which
is necessary for the recycling of vitamin K. This leads to the production of inactive forms of clotting
factors II, VII, IX, and X .
11. A patient with hyperthyroidism presents with exophthalmos and pretibial myxedema. These
findings are most characteristic of which underlying mechanism?
A. Low TSH receptor antibodies
B. Autoimmune stimulation of the TSH receptor
C. Destruction of thyroid follicles by T-cells
D. Excess iodine intake
Correct Answer: B. Autoimmune stimulation of the TSH receptor
Rationale: Exophthalmos and pretibial myxedema are pathognomonic for Graves' disease, an
autoimmune disorder where thyroid-stimulating immunoglobulins (TSI) bind to and activate the TSH
receptor, leading to uncontrolled thyroid hormone production .
12. A 56-year-old woman with fatigue has high TSH and low free T4. What is the diagnosis?
A. Secondary hypothyroidism
B. Thyrotoxicosis
C. Primary hypothyroidism
D. Subclinical hyperthyroidism
Examination Questions And Correct Answers
(Verified Answers) Plus Rationales
1. A 23-year-old man presents with fever, cough, and rusty sputum. Lung exam shows crackles in the
right lower lobe. Chest X-ray shows lobar consolidation. The most likely organism is:
A. Haemophilus influenzae
B. Mycoplasma pneumoniae
C. Streptococcus pneumoniae
D. Chlamydophila pneumoniae
Correct Answer: C. Streptococcus pneumoniae
Rationale: Streptococcus pneumoniae is the most common cause of community-acquired lobar
pneumonia. The classic presentation includes fever, cough, and "rusty" sputum, which is due to blood
from inflammation. Lobar consolidation on X-ray is a hallmark finding .
2. A 56-year-old woman presents with fatigue, cold intolerance, and weight gain. Lab results show a
markedly elevated TSH and low free T4. What is the most likely diagnosis?
A. Secondary hypothyroidism
B. Thyrotoxicosis
C. Primary hypothyroidism
D. Subclinical hyperthyroidism
Correct Answer: C. Primary hypothyroidism
Rationale: This pattern of elevated TSH with low free T4 is diagnostic of primary hypothyroidism. The
elevated TSH indicates that the thyroid gland itself is not producing enough hormone, and the pituitary
is trying to compensate by releasing more TSH .
3. A 68-year-old man with Parkinson's disease presents with bradykinesia, rigidity, and a resting
tremor. The underlying pathophysiology involves the loss of neurons in which area of the brain?
A. Loss of dopamine in the globus pallidus
B. Loss of serotonin in the substantia nigra
,C. Loss of dopamine from the substantia nigra pars compacta
D. Loss of norepinephrine from the locus coeruleus
Correct Answer: C. Loss of dopamine from the substantia nigra pars compacta
Rationale: Parkinson's disease is characterized by the progressive degeneration of dopaminergic
neurons in the substantia nigra pars compacta. This leads to a dopamine deficiency in the striatum,
causing the classic motor symptoms of bradykinesia, rigidity, and resting tremor .
4. A 45-year-old man presents with severe right-upper-quadrant pain that radiates to the right
shoulder. The pain began several hours after a large, fatty meal. On exam, he has a positive Murphy
sign. What is the most likely diagnosis?
A. Acute pancreatitis
B. Peptic ulcer disease
C. Acute cholecystitis
D. Acute appendicitis
Correct Answer: C. Acute cholecystitis
Rationale: The presentation of post-prandial (especially fatty meal) right upper quadrant pain with a
positive Murphy sign (inspiration halts during palpation of the RUQ) is classic for acute cholecystitis,
most commonly due to gallstones .
5. A 24-year-old man presents with dysuria and a purulent urethral discharge. A Gram stain of the
discharge reveals Gram-negative diplococci. What is the most appropriate treatment?
A. Oral erythromycin
B. Oral amoxicillin
C. Intramuscular ceftriaxone and oral doxycycline
D. Oral metronidazole
Correct Answer: C. Intramuscular ceftriaxone and oral doxycycline
Rationale: The presence of Gram-negative diplococci in a male with urethritis is indicative of Neisseria
gonorrhoeae. The standard of care is dual therapy with ceftriaxone (for gonorrhea) and doxycycline (to
cover for concurrent Chlamydia trachomatis infection, which is a common co-infection) .
6. A 20-year-old college student presents with severe fatigue, sore throat, and lymphadenopathy. A
peripheral blood smear shows atypical lymphocytes. What is the most likely causative virus?
A. Cytomegalovirus (CMV)
B. Adenovirus
,C. Epstein-Barr virus (EBV)
D. Herpes simplex virus-1 (HSV-1)
Correct Answer: C. Epstein-Barr virus (EBV)
Rationale: The triad of fever, pharyngitis, and lymphadenopathy, along with the presence of atypical
lymphocytes on a blood smear, is classic for infectious mononucleosis, which is caused by the Epstein-
Barr virus .
7. A 50-year-old man with a history of alcohol use disorder presents with epigastric pain radiating to
the back. Labs show elevated serum amylase and lipase. What is the initial management?
A. Immediate surgical consultation
B. NPO status and aggressive IV fluid resuscitation
C. Endoscopic retrograde cholangiopancreatography (ERCP)
D. Broad-spectrum antibiotics
Correct Answer: B. NPO status and aggressive IV fluid resuscitation
Rationale: The presentation is consistent with acute pancreatitis. Initial management is supportive, with
bowel rest (NPO) to reduce pancreatic stimulation and aggressive intravenous fluid resuscitation to
maintain intravascular volume and prevent pancreatic necrosis .
8. A 7-year-old child presents with a sore throat and a diffuse, erythematous, "sandpaper-like" rash
on the trunk. The tongue appears red and swollen, described as a "strawberry tongue." What is the
most likely cause?
A. Coxsackie virus
B. Adenovirus
C. Streptococcus pyogenes
D. Staphylococcus aureus
Correct Answer: C. Streptococcus pyogenes
Rationale: These are classic signs of scarlet fever, which is caused by group
A Streptococcus (Streptococcus pyogenes) that produces an erythrogenic toxin. The sandpaper rash and
strawberry tongue are hallmark features .
9. A 40-year-old man with a history of alcoholism presents with macrocytic anemia and paresthesias
in his lower extremities. Which vitamin deficiency is most likely?
A. Folate
B. Vitamin B2 (riboflavin)
, C. Vitamin B12 (cobalamin)
D. Vitamin C
Correct Answer: C. Vitamin B12 (cobalamin)
Rationale: While both folate and B12 deficiencies can cause macrocytic anemia, the presence of
neurologic deficits (paresthesias, subacute combined degeneration) points specifically to a vitamin B12
deficiency. Folate deficiency does not cause neurologic symptoms .
10. A patient with a history of atrial fibrillation is prescribed warfarin. The therapeutic effect of
warfarin is monitored by the International Normalized Ratio (INR) because it works by:
A. Activating vitamin K
B. Inhibiting vitamin K epoxide reductase
C. Directly blocking thrombin
D. Activating protein C
Correct Answer: B. Inhibiting vitamin K epoxide reductase
Rationale: Warfarin is a vitamin K antagonist. It inhibits the enzyme vitamin K epoxide reductase, which
is necessary for the recycling of vitamin K. This leads to the production of inactive forms of clotting
factors II, VII, IX, and X .
11. A patient with hyperthyroidism presents with exophthalmos and pretibial myxedema. These
findings are most characteristic of which underlying mechanism?
A. Low TSH receptor antibodies
B. Autoimmune stimulation of the TSH receptor
C. Destruction of thyroid follicles by T-cells
D. Excess iodine intake
Correct Answer: B. Autoimmune stimulation of the TSH receptor
Rationale: Exophthalmos and pretibial myxedema are pathognomonic for Graves' disease, an
autoimmune disorder where thyroid-stimulating immunoglobulins (TSI) bind to and activate the TSH
receptor, leading to uncontrolled thyroid hormone production .
12. A 56-year-old woman with fatigue has high TSH and low free T4. What is the diagnosis?
A. Secondary hypothyroidism
B. Thyrotoxicosis
C. Primary hypothyroidism
D. Subclinical hyperthyroidism
