A Case of Isoniazid-Induced Thrombocytopenia: Recovery with Immunoglobulin Therapy

Treatment for a 51-year-old man with pulmonary tuberculosis was initiated with isoniazid, rifampicin, ethambutol, and pyrazinamide, and discontinued after 3 weeks because of skin rash and itchiness. Isoniazid monotherapy was restarted after 2 weeks. Two days later, the platelet count decreased from 150 to 4×103/mm3. Despite platelet transfusion and oral corticosteroid treatment, the platelet count did not recover. However, after a 2-day administration of intravenous immunoglobulin, the platelet count recovered to 209×103/mm3. This report describes a case of isoniazid-induced thrombocytopenia that was reversed with intravenous immunoglobulin, thus highlighting the efficacy of this treatment for this rare condition.