The spectrum of kidney function alterations in adolescents with a solitary functioning kidney

• Published in: Pediatric nephrology (Berlin, West) Vol. 36; no. 10; pp. 3159 - 3168
• Main Authors: Grapin, Mathilde, Gaillard, François, Biebuyck, Nathalie, Ould-Rabah, Melissa, Hennequin, Carole, Berthaud, Romain, Dorval, Guillaume, Blanc, Thomas, Hourmant, Maryvonne, Kamar, Nassim, Rostaing, Lionel, Couzi, Lionel, Garcelon, Nicolas, Prié, Dominique, Boyer, Olivia, Bienaimé, Frank
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.10.2021; Springer Nature B.V; Springer Verlag
• Subjects: Adolescent; Adolescents; Adult; Aged; Child; Creatinine; Cystatin C; Epidermal growth factor receptors; ErbB Receptors; Fibroblast growth factor 23; Glomerular Filtration Rate; Humans; Hypertrophy; Kidney - physiology; Kidneys; Life Sciences; Medicine; Medicine & Public Health; Nephrology; Original Article; Parathyroid hormone; Pediatrics; Solitary Kidney; Teenagers; Urinary tract; Urology; Young Adult; Children; Solitary functioning kidney; Measured glomerular filtration rate; Glomerular filtration rate
• ISSN: 0931-041X; 1432-198X
• DOI: 10.1007/s00467-021-05074-z

Background A precise assessment of glomerular filtration rate is key to delineate the care of children with a solitary functioning kidney (SFK). Data regarding measured GFR (mGFR) in this population is restricted to a single study of 77 individuals, which suggested that a GFR estimation (eGFR) method based on creatinine and cystatin C (eGFR-CKiD2) performed better than Schwartz’s equation (eGFR-Schwartz). Methods We measured GFR in 210 consecutive adolescents (7 to 22 years old) with an SFK referred to our institution between 2014 and 2019 and in 43 young candidates for kidney donation (18 to 25 years old). We compared the distribution of mGFR in both groups and determined the factors associated with reduced mGFR in adolescents with an SFK. We further compared different eGFR formulas with mGFR and assessed the association of mGFR and eGFRs with PTH and FGF23, two early indicators of GFR reduction. Results While adolescents with an SFK had a similar median mGFR to healthy controls (103 ± 24ml/min/1.73m 2 vs. 107 ± 12 ml/min/1.73m 2 ), the fraction of individuals with an mGFR below 90 ml/min/1.73m 2 was higher in patients with SFK (23% vs. 5% in controls; P = 0.005). Multiple linear regression identified older age, ipsilateral abnormalities of the urinary tract, lack of compensatory hypertrophy, and treated hypertension as independent factors associated with reduced mGFR. A smaller bias using eGFR-Schwartz (95% confidence interval (95%CI): 3 to 7) was revealed when compared to other eGFR. Compared to eGFR-Schwartz, mGFR showed a stronger correlation with PTH ( r  = 0.04 vs. r  = 0.1) and FGF23 ( r = 0.03 vs. r  = 0.05). Conclusion SFK is not a benign condition, since 20% of the patients display altered kidney function. Our results raise caution regarding the use of the cystatin-based equation. mGFR shows a better ability than eGFR-Schwartz to differentiate patients showing early homeostatic adaptation to GFR reduction. Graphical abstract