Background: Accurate kidney function assessment is crucial in transplantation due to its impact on survival and the procedure's inherent risks. However, estimating glomerular filtration rate (GFR) is challenging due to influences from age and body composition, especially in pediatric and elderly populations. Recently, D-Ser and D-Asn, rare enantiomers of amino acids, have been identified as GFR biomarkers that are relatively unaffected by body composition. We investigated whether estimating GFR using these two D-amino acids could be applicable across a wide age range.
Methods: We analyzed data from two cross-sectional observational cohorts: 366 living kidney transplant donors and recipients, and 27 pediatric patients. Using a dataset of 244 adult patients, we developed GFR estimation formulae based on blood levels of D-Ser and D-Asn using linear regression analyses. We validated the formulas’ performance in 122 adults and 27 children.
Results: The D-amino acids-based equation was 60.4 x D-Ser-0.450 x D-Asn-0.304 x 0.916 (if female). For D-amino acid-based equations, age was unnecessary. The performance of the established equations was equivalent to that of creatinine-based equations: bias, 9.1 [8.0-11.2], precision, 11.1 [8.8-14.2], and accuracy (P30), 0.82 [0.73-0.89]. Strikingly, in the pediatric cohort, D-amino acid-based eGFR correlated well with conventional pediatric eGFR.
Conclusions: The performance of D-amino acids-based eGFR is compatible with the conventional eGFR. This approach shows minimal age and sex influence, making it broadly applicable from pediatric to geriatric populations and allowing the extrapolation of adult evidence to children.