Lack of influence of fetal hemoglobin levels or erythrocyte indices on the severity of sickle cell anemia.

A B S T R A C T Persoins with sickle cell anemiiia who have elevated fetal hemoglobin or lowered erythrocyte mean corpuscular volume are reputed to have less severe clinical manifestations anid a greater probability of survival. This study examiines the relationship between seven clinical indicators of morbidity in sickle cell anemia and seven hematological parameters that were collected fromn 214 patients. Risks of sickle cell crisis, acute chest syndromiie, hospital admissions, cerebrovascular accident, aseptic necrosis, meningitis/septicemia, and death were used as indicators of morbidity. The hematological parameters included percent fetal hemoglobin, absolute fetal hemoglobin, percent hemoglobin A2, hemoglobin concentration, packed cell volume, mean corpuscuilar volume, and mean corpuscular hemoglobin concentration. Statistical analyses of the data showed no relationship between the hematological paramiieters and six of the seven clinical indicators of the severity of sickle cell anemia. The only significant finding was an increased risk of stroke in those patients with lower levels of fetal hemnoglobin. Therefore, with this exception, there is no predictable relationship between morbidity and mortality in sickle cell anemia and levels of fetal heimoglobin or erythrocyte indices. Thus, the general belief that there is an association between severity of sickle cell anemia and the levels of fetal hemoglobin has not been established.