A persistent severe autoimmune hemolytic anemia despite apparent direct antiglobulin test negativization.

BACKGROUND AND OBJECTIVE: Not all cases of autoimmune hemolytic anemia (AIHA) are diagnosed by the direct antiglobulin test (DAT). We present and discuss a simple method of enhancing the sensitivity of the standard DAT. DESIGN AND METHODS: We report the case of a five-month-old child diagnosed with a severe IgG-mediated AIHA, characterized by quick DAT negativization despite clinical worsening. Warm AIHA with negative DAT, possibly due to a low affinity autoantibody, unresponsive to conventional therapy, was hypothesized. RESULTS: The DAT resulted strongly positive with anti-IgG serum using a 4C saline for erythrocyte washing, to reduce the dissociation of the supposed low affinity autoantibody. Very intensive cytoreductive treatment was administered twice until clinical remission was obtained. INTERPRETATION AND CONCLUSIONS: The clinical course of AIHA can be dissociated by the DAT. Since autoantibody-mediated hemolysis with negative DAT rarely occurs, once other causes of high reticulocyte count anemia have been ruled out, the DAT after ice-cold saline washing could be a useful and easy means of corroborating the diagnosis of AHIA, when traditional methods fail.