Reversible splenic hypofunction in hypertransfused children with homozygous sickle cell disease.

Functional hyposplenism, as documented by technetium 99 metastable sulfur colloid spleen scan and increased pocked erythrocyte count (also known as a pit count), is well described in children under 2 years of age with homozygous sickle cell anemia. We evaluated the clinical course and splenic function of 16 patients with sickle cell anemia (ages 3 to 20 years) on a hypertransfusion program for more than 6 months following a cerebrovascular accident. Patients were followed with simultaneous spleen scan and pitted erythrocyte count using direct interference contrast microscopy. Pit counts were taken prior to each transfusion and hemoglobin S level maintained at less than 20%. With the exception of two patients, splenic function was recovered only in those patients who were younger than 10 years of age at the time transfusion was initiated. There were no serious bacterial infections or other complications of sickle cell anemia documented in the hypertransfused group. Based on our results and the literature review, we conclude that some patients with sickle cell anemia receiving intensive hypertransfusion therapy for a cerebrovascular accident recover a normal splenic phagocytic function. Age and level at which the hemoglobin S is maintained are important factors in reestablishing splenic phagocytic function.