MD Medical Doctor General 5

Question 1

A 40-year-old man presents with symmetric proximal muscle weakness, elevated CK, and a heliotrope rash around the eyes. What is the most likely diagnosis?

Accepted Answer

Dermatomyositis

Answer

Dermatomyositis presents with proximal muscle weakness, elevated CK, and characteristic skin findings including heliotrope rash and Gottron's papules.

Question 2

Which mechanism is responsible for the antiplatelet effect of aspirin?

Accepted Answer

Irreversible inhibition of cyclooxygenase, blocking thromboxane A2 synthesis

Answer

Aspirin irreversibly acetylates COX-1 in platelets, permanently blocking thromboxane A2 synthesis for the platelet's lifespan (~10 days).

Question 3

A 55-year-old woman with known cirrhosis presents with confusion, asterixis, and elevated ammonia. What precipitant should be ruled out first?

Accepted Answer

Gastrointestinal bleeding

Answer

GI bleeding is a common precipitant of hepatic encephalopathy because blood protein in the gut is metabolized by bacteria to ammonia, worsening encephalopathy.

Question 4

A 22-year-old with sickle cell disease presents with sudden onset severe pain in the long bones. Temperature is 38.5°C. The most common organism causing osteomyelitis in sickle cell patients is:

Accepted Answer

Salmonella species

Answer

While S. aureus is the most common cause of osteomyelitis in the general population, Salmonella is disproportionately common in sickle cell disease due to functional asplenia.

Question 5

A patient with COPD exacerbation on supplemental oxygen develops increasing somnolence. ABG shows pH 7.30, PaCO2 65 mmHg, PaO2 75 mmHg. What is the most likely cause of somnolence?

Accepted Answer

Hypercapnic narcosis from CO2 retention

Answer

In COPD patients with chronic hypercapnia, elevated oxygen delivery removes the hypoxic drive, leading to hypoventilation and CO2 narcosis.

MD - Doctor of Medicine Practice Test

MD - Doctor of Medicine Practice Test

MD Medical Doctor General 5