Abstract
Background and Purpose: In Japan, estimated glomerular filtration rate (eGFR) based on creatinine (Cr), cystatin C (CysC), and β2-microglobulin (β2MG) is commonly used to evaluate kidney function in children. However, discrepancies between these eGFR values have been observed in clinical practice. This study aimed to investigate the consistency between the measured glomerular filtration rate (mGFR) using the inulin clearance test (Cin), eGFR values derived from Cr, CysC, and β2MG, as well as eGFR based on 24-hour creatinine clearance (CCr).
Methods: This retrospective study included 120 patients (83 boys) aged 3 months to 18 years with chronic kidney disease who underwent Cin testing at our hospital between 2016 and 2023. The mGFR values were compared with Cr-eGFR, CysC-eGFR, β2MG-eGFR, and CCr-eGFR for each subject. The mean error (ME) was calculated through Bland-Altman analysis to evaluate the validity of each estimate.
Results: A total of 167 Cin tests were conducted. The mean values (ml/min/1.73 m2) of each test were as follows: mGFR 63.5±32.6, Cr-eGFR 63.3±26.2, CysC-eGFR 68.8±28.3, β2MG-eGFR 87.3±40.5, and CCr-eGFR 57.4±26.9. The Cr-eGFR showed the greatest similarity to mGFR, with Bland-Altman analysis confirming that Cr-eGFR was the most valid and reliable method for estimating mGFR.
Conclusion: Cr-eGFR provides the most accurate estimate of mGFR compared to other methods. The reasons for the observed discrepancies and the potential need for new estimation formulas warrant further discussion.
