Iron Overload in Acute Myelogenous Leukemia after Bone Marrow Transplantation.

Children with acute leukemias typically receive RBC transfusions during the course of their treatment. However, the severity and significance of transfusional iron overload is not known in this patient population. Earlier, we reported elevated serum ferritin (SF) in 5 patients with AML who received HLA-identical sibling bone marrow transplantation (BMT). However, SF has a wide predictive interval for liver iron concentration (LIC) in thalassemia and sickle cell disease and the current recommendation is to measure LIC to estimate total body iron burden. Further exploration of the SF-to-LIC ratio (SF/LIC) to investigate the relationship between SF and LIC has shown ratio differences by specific disease (SCD, thalassemia, genetic hemochromatosis), transfusion status and use of chelation. The reasons for these differences are not presently known. In this study LIC was measured within 2 weeks of serum ferritin (SF), in 8 AML patients after transplantation, to explore the significance of the elevated SF and to determine the range and character of the SF/LIC ratio after BMT for AML. LIC was measured (1–4 year after BMT) by a low temperature SQUID biosusceptometer system (Ferritometer^®) under the standardized Hamburg-Torino-Oakland protocol. The range for LIC in healthy individuals measured by SQUID is 90–340 mg/g _{wet weight}. The median serum ferritin was 1227 (582–1723) μg/l and the median LIC was 1284 (751–1612) mg/g _{wet weight} or approximately 4 times greater than the upper limit of normal. ALT was measured in 4 patients of which 2 were mildly elevated. Neither LIC nor SF changed over the interval of follow-up extending to 3 years in 2 patients (aged 11.5y and 14.5 y) who returned annually for LIC measurements. The ratio of SF/LIC ranged from 0.5 to 1.4 (median: 0.9) in the patients with AML. This compares to ratios of 1.2 (0.6–2.6) in regularly transfused sickle cell disease patients (n=45), 0.87 (0.23–2.7) in transfusion dependent thalassemia patients and 0.32 (0.05–0.57) in transfusion independent thalassemia patients. These preliminary observations suggest that children with acute leukemias who undergo bone marrow transplantation develop significant transfusion related iron accumulation. Additional investigation should be undertaken to determine if AML patients would benefit from iron reduction therapy by phlebotomy after BMT.