The 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. (Arch Intern Med. 1994;154:1620-1624)