Idiosyncratic rifabutin-induced leukopenia and SIADH: case report and review.

Rifabutin is increasingly critical for treatment of atypical mycobacterial infections. One of its serious adverse effects is leukopenia. When encountering rifabutin-induced leukopenia, clinicians are faced with the dilemma of whether to lower the dosage of rifabutin or discontinue it because existing literature does not indicate whether rifabutin-induced leukopenia is dose related or idiosyncratic. We report the first established case of idiosyncratic rifabutin-induced leukopenia in an immunocompetent man treated for pulmonary Mycobacterium avium complex infection. The patient also developed rifabutin-induced syndrome of inappropriate antidiuretic hormone (SIADH), which also has not been previously reported.