Sickle Cell Disease - Treatment

Highlights	Diagnosis	Lifestyle Changes
Introduction	Outlook	Resources
Risk Factors	Complications	References
Symptoms	Treatment

Treatment

Research is ongoing toward identifying the biologic and chemical activities that promote or protect against the sickle cell process. Currently, experimental treatments focus on the basic processes that cause the red blood cells to sickle in the first place. There are three basic modes of treatment:

Stimulation of production of healthy fetal hemoglobin in order to inhibit the sickling process.
Blocking dehydration in the cells.
Transplantation of bone marrow or stem cells from healthy donors so that normal hemoglobin is produced rather than hemoglobin S.

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Drugs that Stimulate Fetal Hemoglobin

Hemoglobin F (HbF, also called fetal hemoglobin) is the form of hemoglobin that exists in the fetus and small infants. Most HbF is later replaced by the hemoglobin that is present in the growing child and adult, although some HbF may persist. Fetal hemoglobin is able to block the sickling action of red blood cells so that infants with sickle cell disease do not develop symptoms of the illness while they still have hemoglobin F. Adults who have sickle cell disease but still retain high levels of hemoglobin F generally have mild disease.

Studies are now reporting that the severity of sickle cell disease can be reduced by using drugs that stimulate production of HbF. Even increases as modest as 4% may have a significant benefits for these patients.

Hydroxyurea. Hydroxyurea (Droxia, Hydrea) destroys cells in the bone marrow, which results in an increase in special cells that can produce HbF. It is currently the only drug in general use to prevent acute sickle cell crises. It appears to have a number of effects on sickle cell:

Hydroxyurea reduces the intensity and frequency of sickle cell crises by nearly 50%. (It does not have any effect on pain, however, once it starts.)
Over time, the drug may improve spleen function, which aids in the immune process, particularly in children.
Hydroxyurea increases water content in red blood cells.
The drug reduces the number of neutrophils, the white blood cells that contribute to the process causing sickle cells to stick to the blood vessel walls. This effect may actually be more protective over time than its effect on increasing levels of hemoglobin F.

Hydroxyurea is now indicated in adults and adolescents with moderate to severe recurrent pain (occurring three or more times a year). The drug is proving to reduce sickling crises and pain, priapism, the number of transfusions, and life-threatening complications in this group. The benefits appear to be long lasting. For example, a 2002 study reported that after 4 years patients who had taken the drug for at least2 years experienced 30% fewer hospitalizations and 58% fewer transfusions than before they took hydroxyurea. In a 9-year study, the drug also reduced mortality rates by about 40%. Hydroxyurea is not a cure-all. Not all patients respond to hydroxyurea, and the best candidates for the treatment are not yet clear. Small studies have reported no protection from damage in the spleen or bones and joints. Effects on stroke and complications in the eye or kidney are not yet known.