Rifampicin-induced adrenal insufficiency in the acquired immunodeficiency syndrome: difficulties in diagnosis and treatment.

Rifampicin, an antituberculous drug, causes increased hepatic metabolism of steroid hormones. We report the case of a patient with the acquired immunodeficiency syndrome treated with rifampicin who had a 'normal' screening test for adrenal insufficiency, yet had clinical evidence of adrenal failure. Diagnostic testing could not be completed due to lack of clinical response to dexamethasone. Both of these findings are due to the unique effects of rifampicin on steroid metabolism.