Background

Methyldopa is an antihypertensive medication the use of which is limited to pregnant women. Alpha-methyldopa commonly induces warm reactive IgG autoantibodies but only rarely leads to symptomatic autoimmune hemolytic anemia with an incidence of approximately one case per million. We report a case of methyldopa-induced autoimmune hemolytic anemia in a 36-year-old primipara woman.

Methods

The patient started methyldopa in the second trimester of pregnancy. Two months later she developed a positive direct antiglobulin test (DAT) and her plasma tested positive for free warm reactive autoantibodies without anemia. The patient continued the drug after delivery and six months later she presented to the emergency unit with jaundice, fatigue and dark urine. Laboratory evaluation on admission revealed low hemoglobin at 6,2 g/dl, elevated lactate dehydrogenase and bilirubin and low haptoglobin. Serologic workup showed a 4+ direct antiglobulin test with anti-IgG only, no complement fixation, and warm reactive autoantibodies in her plasma and in an eluate prepared by acid elution.

Results

Withdrawal of methyldopa and corticosteroid therapy resulted in rapid increase of the hemoglobin level within a few days. At birth the newborn had shown a positive DAT without maternal ABO-incompatibility, a bilirubin level near the upper and hemoglobin level near the lower reference interval. Since there were no clinical signs of erythroblastosis further treatment was not required.

Conclusion

Diagnosis of the drug independent subtype of drug induced autoimmunhemolytic anemia can not be made by serologic tests alone. It requires detailed medication history, clinical presentation and course in combination with serologic findings. Thus obstetricians, family doctors and immunohematologists providing care for pregnant women should be aware of this possibly hazardous phenomenon.

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