Excess body iron could persist for years after allogeneic hematopoietic cell transplantation (HCT) with possible deleterious sequels. An iron depletive therapy with phlebotomy seems rational. Kinetics of iron removal by phlebotomy without erythropoietin support in non-thalassemic adult patients with iron overload after HCT and the impact of pre- and post-HCT hemochromatosis (HFE) genotype on iron mobilization were investigated.
Patients and methods: Phlebotomy was initiated in 61 recipients of allografts due to hematologic malignancies (median age 48 years) after a median of 18 months. The prephlebotomy median serum ferritin (SF) was 1697ng/ml and the median number of blood transfusions 28 units. Alanine aminotransferase (ALT)/aspartate aminotransferase (AST), alkaline phosphates (AP), and bilirubin were elevated in 55.7%, 64% and 11.5% patients respectively. HFE-genotype was elucidated by polymerase chain reaction using hybridization probes and melting curve analysis.
Results: Phlebotomy was well-tolerated irrespective of age or conditioning. A negative iron balance in 80% of patients (median SF 1086 ng/ml) and a rise in hemoglobin were observed (p<0.0001). Higher transfusional burden and SF were associated with a greater iron mobilization per session (p=0.02). In 58% of patients, a plateau after an initial steady decline in SF was followed by a second decline under further phlebotomy. The improvement in ALT (p=0.002), AST (p=0.03), AP (p=0.01), and bilirubin (p<0.0001) did not correlate with the decline in SF. Mutant HFE-gene variants were detected in 14/55 (25%) pre-HCT and 22/55 (40%) patients post-HCT. Overall, dissimilar pre- and posttransplantational HFE-genotypes were detected in 20/55 (40%) patients. Posttransplantational mutant HFE variants correlated with a slower decline in SF (p=0.007).
Conclusions: Phlebotomy is a convenient therapy of iron overload in survivors of HCT. A negative iron balance and a rise in hemoglobin were observed in the majority of patients. Liver dysfunction improved irrespective of SF reduction suggesting a probable rapid decline of the deleterious labile plasma iron. In recipients of grafts with mutant HFE variants a "mixed chimerism" of HFE in body tissues might be created with a change in the set point for iron regulation. The transient plateau in SF after an initial decline might reflect iron mobilization from various tissues.
Keywords: Iron overload; allogeneic HCT; ferritin; phlebotomy.