Falls in older adult — ABIM Board MCQ

Instant feedback + full explanation. One question, done properly.

EasyGeneral Internal MedicineFalls in older adultABIM Board

An 84-year-old woman has had several falls during the week after starting amitriptyline for painful peripheral neuropathy. She reports new dry mouth and lightheadedness when standing. Her blood pressure decreases from 138/74 mm Hg while supine to 110/62 mm Hg after standing. Neurologic examination is unchanged from baseline. Which of the following is the most likely cause of her falls?

Educational content. Not a substitute for clinical judgement or local policy.

Reveal the answer and explanation

Correct answer: D — Adverse effects of amitriptyline

Amitriptyline is a tricyclic antidepressant with strong antimuscarinic activity and alpha-1-adrenergic blockade. Dry mouth reflects its anticholinergic effect, whereas alpha-1 blockade contributes to orthostatic hypotension, positional dizziness, and falls. Older adults are especially susceptible to these adverse effects. The close temporal relationship to starting the medication and the unchanged neurologic examination make amitriptyline the most likely cause. Adrenal insufficiency can cause hypotension but does not explain the medication timing and would usually have additional systemic or electrolyte findings. Vestibular neuritis causes sustained vertigo rather than orthostatic symptoms. Progressing neuropathy would produce new sensory, proprioceptive, or gait abnormalities. Cryoglobulinemia would require evidence of hepatitis C and systemic manifestations such as purpura, arthralgia, renal disease, or worsening neuropathy.

Reference: DailyMed/FDA labeling. Amitriptyline Hydrochloride Tablets, USP, Geriatric Use and Adverse Reactions sections. Revised October 2025. https://dailymed.nlm.nih.gov/dailymed/fda/fdaDrugXsl.cfm?setid=c072c1b3-ed8a-4f1e-ba6c-580a2b2c8f58&type=display