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

Pit counts, using direct interference phase-contrast microscopy (Normansky Optics) were carried out on 32 HbSS patients, aged 3-17 years. The influence of age and splenic size on the counts was also investigated. Nine (9) HbAS and HbAA age and sex-matched, healthy individuals served as controls. The mean +/- SD counts in the 3 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%) of the patients had counts in excess of 10%, while 8 (25%) had less than 3.5%. Five patients who had gross splenomegaly had a mean count of 4.3 +/- 1.9%, which was significantly lower than the figure of 12.3 +/- 7.9% for the patients without splenomeglay (p less than 0.001), thus demonstrating retained reticuloendothelial function in such patients.