SEVERE MEGALOBLASTIC-ANEMIA IN A PATIENT RECEIVING LOW-DOSE METHOTREXATE FOR PSORIASIS

Severe megaloblastic anemia with a normal white blood cell and platele t count developed in a patient with psoriasis vulgaris who was receivi ng long-term, low-dose methotrexate. We believe she had methotrexate-i nduced folate deficiency anemia with isolated inhibition of the erythr ocytic bone marrow line. We review hematologic toxicity from low-dose methotrexate. Physicians caring for patients who receive low-dose meth otrexate should be aware that an increase in the erythrocyte mean corp uscular volume may be a useful indicator of folate deficiency and impe nding toxicity. In addition, folate supplementation may prevent this t oxicity (even in patients who do not appear clinically to be folate de ficient), although whether methotrexate efficacy diminishes is controv ersial.