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Alpha blocker orthostatic symptoms — USMLE Step 3 MCQ

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ModerateAmbulatory Medicine / Primary CareAlpha blocker orthostatic symptomsUSMLE Step 3

A 72-year-old man starts tamsulosin for bothersome lower urinary tract symptoms. Three days later he feels lightheaded when standing from bed. Blood pressure is 132/76 mm Hg supine and 104/62 mm Hg standing. He has no chest pain or focal neurologic deficits. Which of the following is the most likely explanation for this patient's findings?

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Correct answer: D — Peripheral alpha-1 adrenergic blockade causing venous pooling

Alpha-1 blockers can cause orthostatic hypotension through peripheral vasodilation and venous pooling, especially after initiation.

Reference: AUA benign prostatic hyperplasia guideline