Causes of chronic orthostatic hypotension.

OBJECTIVE: To determine the frequency of various causes of orthostatic hypotension.
DESIGN: Survey.
SETTING: Tertiary referral center. PATIENTS: One hundred patients with moderate to severe orthostatic hypotension.
RESULTS: Twenty-seven percent of the patients had primary autonomic failure, 35% had secondary autonomic failure, and 38% had hypotension without evidence of generalized autonomic degeneration.
CONCLUSIONS: In a tertiary referral center, only a minority of patients with severe orthostatic hypotension will have Shy-Drager syndrome or Bradbury-Eggleston syndrome as their primary disease. Occasional patients who initially appear to have Bradbury-Eggleston syndrome ultimately prove to have Shy-Drager syndrome or paraneoplastic autonomic failure. Antidepressant drugs, even in low doses, remain a major overlooked cause of orthostatic hypotension.