[Rifampicin-induced severe thrombocytopenia in a patient with miliary tuberculosis]

A 74-year-old female visited a local clinic complaining of fever on January 21, 2002. A chest X-ray and a chest computed tomography (CT) showed diffuse micronodules in all lung fields, which strongly suggested miliary tuberculosis. On January 23, she was referred to our hospital for further examinations. Though sputum was negative on smear, culture, and polymerase chain reaction (PCR) for M. tuberculosis, bone marrow aspirate examined on admission revealed epithelioid granuloma. Therefore we diagnosed her as a miliary tuberculosis, and she was treated with 300 mg of Isoniazid (INH), 450 mg of Rifampicin, and 750 mg of Streptomycin (SM) daily. Five days later, severe thrombocytopenia (platelet count 0.3 x 10(4)/microliter) was observed. We immediately discontinued all antituberculous drugs and administered concentrated platelets and immune globulin. Platelet-associated IgG was detected, and megakaryocytes were slightly increased in moderately hypocellular marrow on the bone marrow aspirate examined again after the appearance of thrombocytopenia. Eleven days after discontinuing all antituberculous drugs, platelet count recovered to 10.2 x 10(4)/microliter. INH, SM, Levofloxacin (LV) were administered afterward, and these drugs did not induce thrombocytopenia. Though challenge administration of RFP was not performed, we concluded that the thrombocytopenia was immunologically induced by RFP. We should keep in mind that RFP-induced thromobocytopenia could appear in the first week after the initiation of therapy.