Assessment of bone marrow and splenic erythropoiesis in myelofibrosis.

The iron uptake in bone marrow and spleen was measured in 29 patients with myelofibrosis using 52Fe and quantitative scanning. In 10 patients, no iron uptake in the marrow could be observed and active erythropoiesis was extramedullary only. In the bone marrow of patients with myelofibrosis, the iron uptake per nucleated red cell was less than that observed in conditions without myelofibrosis or extramedullary erythropoiesis. Increasing splenic iron uptake was likely to be associated with a decreasing bone marrow iron uptake and was related to the size of the spleen. The data suggest that in myelofibrosis, the spleen dominates iron uptake through intense erythropoiesis and a high splenic blood flow, thus restraining iron supply to the bone marrow.