The significance of spleen size in children with sickle cell anemia

Abstract

It is well established that splenic dysfunction occurs in early childhood in sickle cell anemia (SCA), although the determinants and consequences of splenic injury are not fully understood. In this study, we examined spleen size and splenic function in 100 children with SCA aged 0-16 years at King's College Hospital in London. Spleen size was assessed by abdominal ultrasound (US) and splenic function by pitted red blood cells (PIT counts). In our cohort, 5.6% of children aged 6-10 years and 19.4% of children aged 11-16 years had no visible spleen on US (autosplenectomy). Splenomegaly was common in all age groups, with 28% of children overall having larger spleens than the average for their age. Only one child had a PIT count suggesting preserved splenic function. We found no correlation between hemoglobin F levels and spleen size, nor was there any difference in spleen size between children treated with or without hydroxyurea. Although there was a trend toward increased spleen length in children with co-inherited α-thalassemia, this did not reach statistical significance. Finally, we found a strong association between erythrocyte deformability measured with oxygen gradient ektacytometry, spleen size, and PIT counts. In conclusion, our results do not agree with the general perception that most children with SCA undergo autosplenectomy within the first decade of life and indicate that loss of erythrocyte deformability contributes to loss of splenic filtration capacity in SCA, as well as phenotypical variations in spleen size.

FIGURE 1

Distribution of spleen size in different age groups. Spleen size is assessed by spleen length measured with abdominal ultrasound. Results are compared to normal values for age. [Color figure can be viewed at wileyonlinelibrary.com]

FIGURE 2

Association between spleen size/splenic function and red blood cell deformability. Top row: Correlation between spleen length, measured with abdominal ultrasound (US), and oxygen gradient ektacytometry‐derived biomarkers. Bottom row: Correlation between splenic function, assessed with pitted red blood cell counts, and oxygen gradient ektacytometry‐derived biomarkers.