Fenoprofen-induced immune hemolysis. Difficulties in diagnosis and complications in compatibility testing

A 70-year-old man developed severe immune intravascular hemolysis and renal failure following ingestion of fenoprofen, a nonsteroidal, anti-inflammatory drug. The patient's red blood cells were sensitized with both IgG and C3d. The serum reacted with normal red blood cells in the presence and absence of the drug. Addition of albumin to the serum inhibited the reactivity with both neat and drug-treated serum. These atypical serologic findings for drug-related immune hemolytic anemia were explained by (1) the measurement of fenoprofen by high performance liquid chromatography (HPLC) in the neat serum; and (2) solid-phase adsorption studies showing that albumin can bind drug, leading to the disappearance of agglutination when albumin is added. This case demonstrates the utility of drug levels and adsorption techniques to confirm the diagnosis of drug-induced immune hemolytic anemia despite the anomalous serologic results which obscured the diagnosis and management of the patient.