Early detection of glomerular dysfunction and renal tubulopathy in children with sickle cell disease in India.

Background: Sickle cell disease causes microvascular occlusion in different vascular beds. In kidneys, it leads to occult glomerular dysfunction causing asymptomatic microalbuminuria, proximal tubulopathy causing hyposthenuria and increased free water loss and distal tubulopathy causing poor urine acidification. We studied the prevalence of various types of renal dysfunction, the ability of different tests to detect it at an early stage and the correlation of these parameters in children receiving hydroxyurea (HU).

Procedure: Fifty-six children (sample size calculated using SAS9.2 package) attending paediatric clinical services in a tertiary care hospital between 2 and 12 years of age diagnosed by high-performance liquid chromatography (HPLC) were enrolled. Their demographic and laboratory data including renal and urine parameters were collected. Parameters like fractional excretion of sodium (FeNa), trans tubular potassium gradient (TtKg) and free water clearance (TcH2O) were derived by calculations. Data were analysed using IBM SPSS Version 21.0 and Microsoft Office Excel 2007.

Results: We found a significant number of children to have microalbuminuria (17.8%), hyposthenuria (30.4%) and impaired renal tubular potassium excretion (TtKg) (81.3%). A significant correlation was found between the dose of HU with urine osmolality (p < 0.0005) and free water clearance (p = 0.002), while all parameters showed a significant correlation with compliance with HU. Derangement in urine microalbumin and TcH2O correlated significantly with low mean haemoglobin levels (<9 g/dl).

Conclusion: Renal dysfunction is common in children with SCD and can be detected early using simple urine parameters and can be prevented with an early and appropriate dosage of HU with good compliance.