Reliability Of Different Estimated Glomerular Filtration Rate As Measures Of Renal Function In Children With Sickle Cell Disease

Background: There is no reliable marker for detecting early renal disease in early children with sickle cell disease (SCD). Estimation of glomerular filtration rate (eGFR) as derived from the height/plasma creatinine formula is dependent on the accuracy of the creatinine analytical method used. The aim of this study was to evaluate different equations for eGFR. Methods: Children aged 5-16 years recruited. mGFR was obtained using plasma disappearance of Inutest/ Iohexol, serum creatinine (SCr) was measured either by standard laboratory method or by tandem mass spectrometry (MSMS). Estimated GFR was then calculated either by "Bedside Schwartz method" or by the full-age spectrum (FAS) equation. Findings: A total of 79 patients (mean age 9.8 +/- 4.0 years). A revised eGFR constant was calculated for Schwartz equation from the slope of the plot of height/plasma creatinine versus mGFR. Mean values for mGFR (132.7 +/- 32.1 ml/min/1.73m2) and eGFR methods compared: eGFR from standard SCr was significantly higher (144.2 +/- 37.3 ml/min/1.73m2, p = 0.008). The MSMS eGFR showed the lowest SD (SD = 27.5), while both FAS eGFR and FAS-height eGFR showed the highest correlation coefficient (r = 0.67). Interpretation: eGFR calculation based on height and SCr determined with MSMS traceable creatinine is more reliable than Schwartz formula using jaffe/enzymatic methods in SCD children.