Hemolytic Anemia Following Intravenous Immunoglobulin Administration: A Cluster of Suspected Cases

Abstract 4332 Background: Hemolytic anemia caused by the passive transfer of isoagglutinins, typically anti-A or anti-B antibodies, is a rare and likely under-recognized complication of intravenous immunoglobulin (IVIG) therapy. The Immunohematology Reference Laboratory at Mayo Clinic Rochester has detected 12 cases of passively acquired isoagglutinins following IVIG administration during the first seven months of this calendar year (January-July 2011). This frequency of detection is much higher than that seen over the three prior calendar years, when only two cases were detected. Given this “cluster” of isoagglutinin detection, we analyzed these 12 cases to determine the clinical significance of this finding as well as characteristics of resulting cases of hemolytic anemia. Materials/Methods: Charts of patients identified as having passively acquired isoagglutinins following IVIG therapy were analyzed for evidence of a significant drop in hemoglobin (defined as >1 g/dL) as well as evidence of hemolysis (elevated lactate dehydrogenase, reticulocytosis, spherocytosis, decreased haptoglobin, indirect hyperbilirubinemia, hemoglobinemia and hemoglobinuria). Cases with a >1 g/dL drop in hemoglobin and two or more of the above findings consistent with hemolysis were considered “confirmed” cases. Those with passively acquired isoagglutinins but without evidence of hemolysis or with an alternative explanation for anemia were considered “asymptomatic”, and cases without a full hemolytic evaluation but still clinically suspicious were categorized as “suspected” cases. Results: Passively acquired isoagglutinins were detected in 11 patients following 12 separate treatments with IVIG (one patient had antibodies noted after two separate treatment episodes >3 weeks apart). Four of these 12 cases were categorized as “confirmed” cases, five as “suspected” and three as “asymptomatic”. The indication for IVIG use was a neurologic disorder in three of the four confirmed cases, with immune thrombocytopenic purpura (ITP) being the indication in the other case. In suspected cases, ITP was the indication in four of the five cases, with the fifth patient carrying a diagnosis of Kawasaki’s disease. During the 7 month period reviewed, 250 unique patients were treated with IVIG, meaning 1.6% of patients (4/250) had confirmed IVIG-associated hemolytic anemia and another 1.6% (4 patients; 5 events) had suspected hemolytic anemia during this period. The mean decrease in hemoglobin was 4.1 g/dL in confirmed cases (range 1.3–7.1 g/dL) and 2.7 g/dL in suspected cases (range 1.7–4.2 g/dL). Eight of nine patients reviewed had blood type A positive; the other was B positive. The median time from initiation of therapy to hemoglobin nadir was eight days in confirmed and three days in suspected cases. The mean dose of IVIG administered in confirmed cases was 300 g (range 180–400 g) and was 162 g (range 50–300 g) in suspected cases. Red cell transfusion was required in three of the four confirmed cases. Privigen™ was the IVIG product utilized in all four confirmed and the first three suspected cases. After removal of Privigen™ from the Mayo Clinic formulary given concerns regarding these cases, two suspected cases of IVIG-associated hemolytic anemia occurred with Gamunex-C™, including one in a patient who previously suffered confirmed hemolysis after receipt of Privigen™. Conclusions: Hemolytic anemia is a rare complication of therapy with IVIG. The rate of hemolytic anemia following IVIG administration over the evaluated period is consistent with previous reports, but it should be noted that these cases were detected without the aid of an active surveillance policy, indicating the actual rate of hemolytic anemia associated with IVIG use was likely greater than that detected by this review. Our series suggests that those with blood type A may be at increased risk for this complication; further work is ongoing to better define risk factors for development of this potentially significant complication of IVIG therapy. Disclosures: Off Label Use: IVIG use in various off-label indications.