Isoniazid-induced Immune Thrombocytopenia

Abstract

Drug-induced thrombocytopenia occurs through immune-mediated platelet destruction, and its management is challenging during tuberculosis treatment. Although rifampicin is the most common drug causing thrombocytopenia, isoniazid can also cause thrombocytopenia. We herein report a 75-year-old man who developed thrombocytopenia during tuberculosis treatment. Platelet-associated immunoglobulin G and a drug-induced lymphocyte stimulation test for isoniazid were positive; no other causes of thrombocytopenia were identified. The patient was diagnosed with isoniazid-induced immune thrombocytopenia, and the platelet count normalized after isoniazid discontinuation. We describe the immunological mechanism of thrombocytosis due to isoniazid, an uncommon cause of thrombocytopenia that physicians should be aware exists.

Keywords: drug-induced immune thrombocytopenia; isoniazid; tuberculosis.

Figure 1.

Chest radiography at the diagnosis showed bilateral nodular shadow and infiltrative shadow of the left lung.

Figure 2.

Clinical course showing the association between the administered drugs and platelet count (A) before and (B) after the transfer to our hospital. INH: isoniazid, RFP: rifampicin, EB: ethambutol, PZA: pyrazinamide, LVFX: levofloxacin, SM: streptomycin, RBT: rifabutin, Plt: platelet

Figure 3.

A histopathological examination of bone marrow showed the partial collection of hematopoietic cells and hypocellularity. No malignant or granulomatous findings were confirmed (Hematoxylin and Eosin staining, ×100).