A 40-year-old man is found to have severe hypertriglyceridemia on routine evaluation. He has no present complaints. Medical history includes hypertension controlled with hydrochlorothiazide and asymptomatic gallstones. His father had a nonfatal myocardial infarction at age 47. The patient does not smoke or consume alcohol. Blood pressure is 130/75 mm Hg and pulse is 70/min. He is prescribed niacin for his hypertriglyceridemia. The patient returns 1 week later due to intense, generalized pruritus and flushing. What is the most likely cause of his complaint?

Question

A 40-year-old man is found to have severe hypertriglyceridemia on routine evaluation.  He has no present complaints.  Medical history includes hypertension controlled with hydrochlorothiazide and asymptomatic gallstones.  His father had a nonfatal myocardial infarction at age 47.  The patient does not smoke or consume alcohol.  Blood pressure is 130/75 mm Hg and pulse is 70/min.  He is prescribed niacin for his hypertriglyceridemia.  The patient returns 1 week later due to intense, generalized pruritus and flushing.  What is the most likely cause of his complaint?

Quizplus · Accepted Answer

Cutaneous flushing and intense generalized pruritus are well-known side effects of high-dose niacin therapy (high dosage is required to treat lipid abnormalities). These effects are explained by niacin-induced peripheral vasodilation, not vasoconstriction (Choice D). The mechanism involved in this reaction is believed to be drug-induced release of histamine and prostaglandins, not a true hypersensitivity reaction (Choice A). The role of prostaglandins is confirmed by the fact that low-dose aspirin can greatly reduce or prevent cutaneous flushing and pruritus if taken 30 minutes before niacin. Therefore, niacin is frequently prescribed with aspirin. Flushing and pruritus usually improve after 2-4 weeks of therapy. (Choice C) Thiazide diuretics do not intensify this reaction, although they may predispose the patient to hypotension. (Choice E) A psychogenic cause of the patient's complaint is unlikely. Educational objective: High-dose niacin therapy to treat lipid abnormalities frequently produces cutaneous flushing and pruritus. This side effect is explained by prostaglandin-induced peripheral vasodilatation and can be reduced by low-dose aspirin.

A 40-Year-Old Man Is Found to Have Severe Hypertriglyceridemia on Routine