Clinical Importance of Treating Iron Overload in Sickle Cell Disease

Hypothesis: The investigators suspect that significant degrees of iron overload in subjects with SCD result in decreased red cell survival, abnormal endothelial function and markedly dysregulated autonomic function. Furthermore, the investigators anticipate that the magnitude of these effects is proportional not only to the magnitude of total body iron stores but also to the duration of exposure to the high iron levels in tissues. Primary objective To determine if red cell survival as assessed by 51Cr red cell survival analysis, hemoglobin level, reticulocyte count, lactic acid dehydrogenase, and plasma hemoglobin in sickle cell patients is related to the degree of iron overload. Secondary objective(s) 1. Determine if the magnitude of endothelial-dependant vasodilation is related to The degree of iron overload. 2. Determine if the degree of change in cardiac beat to beat variability in response to hypoxic exposure or to cold exposure ("cold-face-test") is related the magnitude of iron overload. The primary measure of iron overload will be MRI determination of liver iron concentration.

Patients with sickle cell anemia often require blood transfusion as part of the treatment for their disease. Since each teaspoon of packed red blood cells contains about 5 mg of iron and humans have no way to get rid of excess iron, the levels of iron in sickle cell patients increase rapidly with each transfusion. Too much iron is extremely dangerous and causes damage to blood vessels, red blood cells, liver, hormone producing glands and heart. It is very difficult to know what damage due to iron overload in sickle cell patients because the sickle cell disease itself causes organ damage to the same organs affected by iron. The purpose of this project is to demonstrate that iron overload significantly increases the morbidity of sickle cell disease and that treatment of the iron overload with Exjade® prevents or attenuates iron-related morbidity. To accomplish this we will screen sickle cell patients with a history of many blood transfusions to see if they have high iron levels. Then we will treat the patients who have very high iron levels with a drug which will remove the iron. Only patients with a very high iron level will be eligible for the treatment. These patients will have been transfused many times before but cannot currently be on blood transfusions. Before we start the treatment we will test the level of anemia, how fast the red cells are being destroyed, how well their blood vessels work and how well their heart works. When the treatment is over, we will repeat these tests and see if there is an improvement. To qualify for this study, you must carry the diagnosis of sickle cell anemia and you must have received 10 or more blood transfusions in your life. You also cannot currently be on a regular transfusion program where you are getting blood transfusions regularly planned more than three times a year.