COMLEX-USA Clinical Medicine - Internal Medicine 1 — Questions and Answers
Question 1: A patient with chronic kidney disease has a serum potassium of 6.8 mEq/L and peaked T waves on EKG. First-line immediate treatment is:
- Sodium bicarbonate IV
- IV calcium gluconate (Correct answer)
- Furosemide IV
- Kayexalate (sodium polystyrene sulfonate)
Correct answer: IV calcium gluconate
IV calcium gluconate immediately stabilizes the cardiac membrane in hyperkalemia, preventing arrhythmia, though it does not lower potassium levels.
Question 2: Which finding on pulmonary function tests is characteristic of obstructive lung disease such as COPD?
- Reduced FVC with normal FEV1/FVC ratio
- Reduced FEV1/FVC ratio (<0.70) (Correct answer)
- Normal spirometry with reduced DLCO
- Increased TLC with normal FEV1/FVC
Correct answer: Reduced FEV1/FVC ratio (<0.70)
Obstructive disease (COPD, asthma) is defined by an FEV1/FVC ratio <0.70, reflecting air trapping and increased expiratory resistance.
Question 3: The most common cause of community-acquired pneumonia (CAP) in otherwise healthy adults is:
- Haemophilus influenzae
- Streptococcus pneumoniae (Correct answer)
- Mycoplasma pneumoniae
- Legionella pneumophila
Correct answer: Streptococcus pneumoniae
Streptococcus pneumoniae remains the most common bacterial cause of CAP in adults across all age groups and severity levels.
Question 4: A patient presents with symmetric proximal muscle weakness, elevated CK, and Gottron's papules. The diagnosis is:
- Polymyositis
- Dermatomyositis (Correct answer)
- Inclusion body myositis
- Fibromyalgia
Correct answer: Dermatomyositis
Dermatomyositis presents with proximal muscle weakness, elevated CK, and pathognomonic skin findings including Gottron's papules (knuckles) and heliotrope rash.
Question 5: In the diagnosis of systemic lupus erythematosus (SLE), which antibody is most specific (though not most sensitive)?
- ANA
- Anti-dsDNA
- Anti-Sm (Correct answer)
- Anti-histone
Correct answer: Anti-Sm
Anti-Smith (anti-Sm) antibody is highly specific for SLE (~99% specific) though present in only ~25% of patients; ANA is most sensitive.
Question 6: Which complication of cirrhosis involves bacterial translocation causing spontaneous infection of ascitic fluid?
- Hepatorenal syndrome
- Hepatic encephalopathy
- Spontaneous bacterial peritonitis (SBP) (Correct answer)
- Hepatopulmonary syndrome
Correct answer: Spontaneous bacterial peritonitis (SBP)
SBP occurs when gut bacteria translocate into ascitic fluid; diagnosed by PMN count >250 cells/mm³ in ascites; treated with cefotaxime.
COMLEX-USA Clinical Medicine - Internal Medicine 1
A patient with chronic kidney disease has a serum potassium of 6.8 mEq/L and peaked T waves on EKG.
First-line immediate treatment is: