The hematopoietic effects of prednisone therapy in four infants with osteopetrosis.

Sequential hematologic studies were performed in four infants with malignant osteopetrosis who received prednisone. Prednisone therapy resulted in decreased liver and spleen size, decreased numbers of circulating immature blood cells, and increased hemoglobin concentration and platelet counts in all infants. The quantity and quality of hematopoietic tissue in bone marrow biopsies improved during prednisone therapy but showed no significant improvement without therapy. Sequential indium 111 chloride scans in one infant showed increased uptake in long bones and pelvis and decreased uptake in liver and spleen during therapy. We conclude that prednisone therapy of infantile osteopetrosis results in increased bone marrow hematopoiesis and decreased extramedullary hematopoiesis.