AZATHIOPRINE INDUCED PANCYTOPENIA-A CASE REPORT

Azathioprine (AZA), a prodrug of 6 mercaptopurine, is an immunosuppressant that can be used as adjunctive therapy with corticosteroids in the treatment of arteritic form of ischemic optic neuropathy. Although myelotoxicity is known to occur while using azathioprine, severe pancytopenia is rarely seen. Patients with thiopurine methyltransferase (TPMT) deficiency are at high risk of developing severe myelosuppression. A 63 year* old female with ischemic optic neuropathy was initiated treatment with oral methylprednisone. As two courses of oral steroids showed no significant improvement, oral azathioprine 25 mg twice daily was added and gradually increased to 50 mg twice daily with relief of symptoms. 6 mo later, she was admitted with acute stroke and lab reports showed low levels of total blood counts or pancytopenia. The patient was put on broad spectrum antibiotics; given injection of granulocyte colony stimulating factor 300 mcg subcutaneously and blood transfusion as correction till counts normalised. She improved over 14 d and on next follow-up counts were in normal range. Causality was assessed by Naranjo causality assessment scale and a probable relationship was obtained between azathioprine and pancytopenia with a score of 6. Variations in TPMT activity occurs due to genetic polymorphism. Physicians should be aware of the possibility of myelosuppression while prescribing azathioprine. Frequent blood count monitoring is the most convenient way to avoid this problem where testing for TPMT deficiency is not possible.