Pitted red cell counts in Nigerian children with sickle cell anemia: correlation with age and splenic size.

Using direct interference phase-contrast microscopy (Normansky Optics), pit counts were performed on 32 HbSS patients, aged 3 to 17 years. The influence of age and splenic size on counts were also investigated. Nine HbSS and 15 HbAA age and sex-matched, healthy individuals served as controls. The mean +/- SD counts in the three groups were 11.1 +/- 9.1%, 1.7 +/- 1.4% and 1.8 +/- 1.7%, respectively. The older SS patients tended to have higher values, but the linear correlation with age was not impressive (r = 0.28). Seventeen (53.1%) patients had counts greater than 10%, while 8 (25%) had less than 3.5%. Five patients with gross splenomegaly had a mean count of 4.3 +/- 1.9%, significantly lower than the figure of 12.3 +/- 7.9% for the patients without splenomegaly (P less than .001), demonstrating retained reticulo-endothelial function in such patients.