FATE OF IRON STORES IN THALASSEMIA AFTER BONE-MARROW TRANSPLANTATION

After successful bone-marrow transplantation (BMT) in thalassaemia, th e individual acquires the pattern of globin synthesis of the donor. We call such an individual ''exthalassaemic after BMT'', a term that und erscores the cure of the genetic defect but maintenance of residual si gns of organ damage due to iron overload and dysfunction acquired duri ng the pretransplant years. We have analysed the extent and fate of ti ssue iron overload in 151 ex-thalassaemic patients after BMT, accordin g to the risk factors of hepatomegaly, hepatic portal fibrosis, and in adequate chelation therapy. Serum ferritin concentrations decreased an d unbound iron binding capacity (UIBC) increased slowly during the yea rs after the transplant. When analysed according to risk group (assign ed at the time of the transplant), ferritin and UIBC returned within t he normal ranges in only the low-risk group (without hepatomegaly or p ortal fibrosis, and with adequate chelation pre-BMT). Ferritin and UIB C were still abnormal 7 years after the transplant in the moderate-ris k group (those with one or two risk factors) and highly abnormal in th e high-risk group (all three risk factors) indicating persistence of, respectively, moderate and severe iron overload at the time of transpl ant. In ex-thalassaemic patients who were studied before and yearly af ter the transplant the extent of haemosiderosis, as judged by staining of liver biopsy samples, decreased during the years after transplant. The degree of iron deposition and rate of post-BMT linear growth seem to influence rate of post-BMT decrease in tissue iron overload in dif ferent risk groups at the time of BMT.