MD Internal Medicine 4 — Questions and Answers
Question 1: A 48-year-old man presents with fatigue, bronze skin discoloration, elevated liver enzymes, and diabetes. Serum ferritin is 2,800 ng/mL and transferrin saturation is 72%. What is the most likely diagnosis?
- Hemolytic anemia
- Hereditary hemochromatosis (Correct answer)
- Wilson's disease
- Alcoholic hepatitis
Correct answer: Hereditary hemochromatosis
Hereditary hemochromatosis (HFE gene mutation) presents with iron overload causing liver disease, diabetes, skin bronzing, and cardiomyopathy; transferrin saturation >45% is a key screening marker.
Question 2: A 25-year-old woman with asthma presents with worsening shortness of breath. Peak flow is 45% of predicted. She has already used her rescue inhaler three times. What is the most appropriate next treatment step?
- Increase inhaled corticosteroid dose
- Administer IV magnesium sulfate as add-on therapy (Correct answer)
- Start oral leukotriene receptor antagonist
- Discharge with oral prednisone burst
Correct answer: Administer IV magnesium sulfate as add-on therapy
In severe acute asthma exacerbations not responding to bronchodilators and steroids, IV magnesium sulfate causes bronchial smooth muscle relaxation and reduces hospital admission rates.
Question 3: A 62-year-old man presents with polyuria, polydipsia, and a serum sodium of 154 mEq/L. Urine osmolality is 80 mOsm/kg after water deprivation; it rises to 600 mOsm/kg after desmopressin administration. What is the diagnosis?
- Nephrogenic diabetes insipidus
- Primary polydipsia
- Central diabetes insipidus (Correct answer)
- Osmotic diuresis
Correct answer: Central diabetes insipidus
Central diabetes insipidus is confirmed when urine concentrates appropriately after exogenous desmopressin (ADH), indicating the kidney can respond but lacks sufficient endogenous ADH.
Question 4: Which of the following best describes the mechanism of warfarin's anticoagulant effect?
- Direct inhibition of thrombin
- Inhibition of vitamin K epoxide reductase, reducing synthesis of factors II, VII, IX, X (Correct answer)
- Activation of antithrombin III
- Irreversible inhibition of platelet COX-1
Correct answer: Inhibition of vitamin K epoxide reductase, reducing synthesis of factors II, VII, IX, X
Warfarin inhibits vitamin K epoxide reductase, preventing recycling of vitamin K, which is required for gamma-carboxylation of clotting factors II, VII, IX, and X.
Question 5: A 55-year-old woman with a BMI of 38 undergoes evaluation for nonalcoholic fatty liver disease. Liver biopsy shows steatohepatitis with bridging fibrosis. Which intervention has the strongest evidence for improving histologic outcomes?
- Ursodeoxycholic acid
- Significant weight loss (>10% body weight) (Correct answer)
- Vitamin E supplementation
- Metformin
Correct answer: Significant weight loss (>10% body weight)
Sustained weight loss of ≥10% body weight is the most effective intervention for NASH, leading to histologic improvement including regression of fibrosis.
Question 6: A 38-year-old man with a history of recurrent DVT and pulmonary embolism is found to have a prolonged aPTT that does not correct with mixing studies. What is the most likely underlying condition?
- Hemophilia A
- Antiphospholipid syndrome (Correct answer)
- Factor V Leiden mutation
- Protein C deficiency
Correct answer: Antiphospholipid syndrome
Antiphospholipid syndrome causes a prolonged aPTT due to lupus anticoagulant that paradoxically does not correct with mixing (due to antibody interference) and is associated with thrombosis, not bleeding.
Question 7: A 66-year-old man presents with progressive exertional dyspnea, bibasilar crackles, and digital clubbing. CT chest shows bilateral basal-predominant honeycombing and traction bronchiectasis. Pulmonary function tests reveal a restrictive pattern with reduced DLCO. What is the most likely diagnosis?
- Sarcoidosis
- Hypersensitivity pneumonitis
- Idiopathic pulmonary fibrosis (Correct answer)
- Cryptogenic organizing pneumonia
Correct answer: Idiopathic pulmonary fibrosis
Idiopathic pulmonary fibrosis (IPF) presents in older men with progressive dyspnea, Velcro crackles, clubbing, and CT showing UIP pattern (honeycombing with basal-predominant traction bronchiectasis).
MD Internal Medicine 4
A 48-year-old man presents with fatigue, bronze skin discoloration, elevated liver enzymes, and diabetes.
Serum ferritin is 2,800 ng/mL and transferrin saturation is 72%.
What is the most likely diagnosis?