MD Medical Doctor General 4

Question 1

A 35-year-old woman presents with progressive muscle weakness that worsens with activity and improves with rest. Edrophonium test is positive. What is the underlying mechanism?

Accepted Answer

Autoantibodies against acetylcholine receptors at the NMJ

Answer

Myasthenia gravis is caused by autoantibodies against nicotinic acetylcholine receptors at the neuromuscular junction, causing fatigable muscle weakness.

Question 2

Which finding best differentiates nephrotic syndrome from nephritic syndrome?

Accepted Answer

Proteinuria >3.5 g/day with hypoalbuminemia and edema

Answer

Nephrotic syndrome is defined by massive proteinuria (>3.5 g/day), hypoalbuminemia, edema, and hyperlipidemia, whereas nephritic syndrome features hematuria and red cell casts.

Question 3

A 50-year-old alcoholic presents with confusion, ataxia, and ophthalmoplegia. Which vitamin deficiency is responsible?

Accepted Answer

Vitamin B1 (thiamine)

Answer

Wernicke's encephalopathy is caused by thiamine (B1) deficiency, presenting with the classic triad of confusion, ataxia, and ophthalmoplegia; treat with IV thiamine.

Question 4

A newborn is noted to have a continuous machinery murmur at the left upper sternal border. Which congenital heart defect is most likely?

Accepted Answer

Patent ductus arteriosus

Answer

Patent ductus arteriosus produces a continuous 'machinery' murmur due to persistent shunting between the aorta and pulmonary artery throughout the cardiac cycle.

Question 5

A 28-year-old woman in her third trimester develops severe headache, blurry vision, and BP of 160/110 mmHg. Urinalysis shows 3+ proteinuria. What is the most appropriate management?

Accepted Answer

IV magnesium sulfate for seizure prophylaxis and delivery planning

Answer

Severe preeclampsia requires IV magnesium sulfate to prevent eclamptic seizures and antihypertensives, with delivery being the definitive treatment.

MD - Doctor of Medicine Practice Test

MD - Doctor of Medicine Practice Test

MD Medical Doctor General 4