Seven days later, she returned to the emergency department (ED) with complaints of progressive back pain and dark urine for two days. Previous history of dark urine was denied. Significant findings included a temperature of 101 o F, scleral icterus, and pale frenulum. Vaginal bleeding was noted but hepatosplenomegaly or costovertebral angle tenderness were not elicited. Laboratory results are shown in Table 1. Peripheral smear showed slight microcytosis with moderate hypochromia and hemoglobinuria was inconclusive because numerous RBCs were found on urinary analysis. Computed tomography (CT) scanning of abdomen and pelvis showed no evidence of occult bleed. The initial working diagnosis in the emergency room was hemolytic uremic syndrome (HUS) and two units of PRBC were requested given her symptomatic anemia.
Q: What is the triad of HUS?A: Hemolytic anemia, thrombocytopenia, and acute renal failure.However, before the PRBC was given, further discussions with the patient revealed a recent transfusion history, raising the suspicion of an alloantibody etiology. A DAT was ordered, which was negative (Table 1). Continued suspicion prompted an eluate study resulting in detection of anti-E, anti-K, and a new anti-Jk b antibody. Phenotyping of two units of PRBC transfused seven days prior were all positive for Jk b antigen, confirming that anti-Jk b was the etiology of her hemolysis. Subsequently, two units of PRBCs negative for antigens Jk b , E, and K were given. The acute renal failure and the markers of hemolysis improved with supportive care, and she received a transfusion card prior to leaving the hospital.
DISCUSSIONDelayed hemolytic transfusion reactions usually occur between one and four weeks post-transfusion (Beers et al., 2006) and represent approximately 11% of all complications of RBC transfusions (Talano et al., 2003). The mechanism is due to alloantibodies formed against One-third of delayed hemolytic transfusion reactions (DHTR) are mediated by the Kidd antibody. We report a case of Kidd-induced DHTR, detailing the diagnostic dilemma in a patient presenting with nonspecific symptoms and inconclusive data. The importance of a full history, including a transfusion history, is emphasized to overcome the dilemma and concludes with a literature review of Kidd (type anti-Jk b ) antibodies.
