Patterns of Liver Iron Accumulation in Patients with Sickle Cell Disease and Thalassemia with Iron Overload

The rate and pattern of iron deposition and accumulation are important determinants of liver damage in chronically transfused patients. To investigate iron distribution patterns at various tissue iron concentrations, effects of chelation on hepatic iron compartmentalization, and differences between patients with sickle cell disease (SCD) and thalassemia major (TM), we prospectively investigated hepatic histologic and biochemical findings in 44 patients with iron overload (35 SCD and 9 TM). The median hepatic iron content (HIC) in patients with TM and SCD was similar at 12.9 and 10.3 mg Fe/g dry weight, respectively (P = 0.73), but patients with SCD had significantly less hepatic fibrosis and inflammation (P < 0.05), less hepatic injury, and significantly less blood exposure. Patients with SCD had predominantly sinusoidal iron deposition, but hepatocyte iron deposition was observed even at low HIC. Chelated patients had more hepatocyte and portal tract iron than non-chelated ones, but similar sinusoidal iron deposition. These data suggest that iron deposition in patients with SCD generally follows the traditional pattern of transfusional iron overload; however, parenchymal hepatocyte deposition also occurs early and chelation removes iron preferentially from the reticuloendothelium. Pathophysiological and genetic differences affecting iron deposition and accumulation in SCD and TM warrants further investigation.