title: Is there a threshold level of fetal hemoglobin that ameliorates morbidity in sickle cell anemia?
abstract: When the clinical manifestations of 272 patients with sickle cell anemia are compared with their level of fetal hemoglobin (HbF), the results suggest that there may be a threshold above which HbF is effective in ameliorating the morbidity of this disease. The age of entry of these SS patients into the study ranged from birth to 56 yr; the average length of follow-up was 11 yr for a total of 3,011 patient-years of clinic observation. HbF was determined quantitatively by microchromatographic procedures; the mean for HbF was 10% +/- 6% with a range from 2% to 32%. For major organ failure, analyzed as termination events of morbidity, such as stroke or aseptic necrosis, the threshold appears to be 10%, whereas for recurrent clinical events, such as crisis or pulmonary disorders, it is 20%. No linear trend was found between HbF levels and morbidity. If a threshold exists, it is important to recognize this fact when attempts are made to raise the level of HbF in patients with sickle cell disease.
mesh_terms: D000293:Adolescent; D000328:Adult; D000375:Aging; D000755:Anemia, Sickle Cell / Q000097:blood* / Q000150:complications / Q000503:physiopathology; D002561:Cerebrovascular Disorders / Q000209:etiology; D002648:Child; D002675:Child, Preschool; D004909:Erythrocyte Indices; D005260:Female; D005319:Fetal Hemoglobin / Q000032:analysis / Q000502:physiology*; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008875:Middle Aged; D010020:Osteonecrosis / Q000209:etiology; D010343:Patient Admission; D012306:Risk
chemical_list: D005319:Fetal Hemoglobin