Urinary Klotho Abnormalities in Children with Sickle Cell Disease

Abstract

Background: Klotho is a trans membrane protein expressed in the renal tubules and serves as an obligatory co-receptor for fibroblast growth factor 23(FGF23) to aid in phosphorus excretion. Prior studies have shown FGF23 resistance in sickle cell disease (SCD). The purpose of the study is to investigate urinary klotho/creatinine (Ur Kl/Cr) in pediatric SCD with normal traditional markers of renal function (eGFR > 90 ml/min and no micro albuminuria) and to compare it with the healthy control population. Methods: Cross-sectional observational study to compare Ur Kl/Cr in pediatric SCD and controls. To do a subgroup analysis among the study population to assess the effect of hydroxyl urea (HU) on Ur Kl/Cr. Results: 20 controls and 22 pediatric SCD were enrolled. In the SCD group, 13 were on treatment with HU. The baseline characteristics of the study and control group were the same. Wilcoxon rank-sum test was used to compare the levels of Ur Kl/Cr ratio between SCD and control. For P value of 0.05, the levels of Ur Kl/Cr were statistically significantly higher in the sickle cell group (752.7 ± 1101.0) over the control group (216.8 ± 225.3). Subgroup analysis in the SCD group showed high Urinary Kl excretion in the non-HU group (1346.7 ± 1523.4) vs. non HU group (341.4 ± 355.3) but not statistically significant. Conclusion: Children with SCD tend to have increased secretion of Ur Kl/Cr compared to control likely due to tubular receptor resistance. HU may reverse this phenomenon by its effect on preventing tubular damage.