On the relationship between glomerular filtration rate and serum creatinine in children

Abstract

The Schwartz formula (eGFR = kL/Scr, with k = 0.55) to determine the estimated glomerular filtration rate (eGFR) in children with chronic kidney disease (CKD), based on length (L) and serum creatinine (Scr) has recently been updated for enzymatic serum creatinine concentrations, resulting in k = 0.413. Based on a meta-analysis, we evaluated the validity of this updated equation and other published equations for healthy children. This is the first time that publicly available data for healthy children of uncorrected and body surface area (BSA)-corrected median GFR have been combined with median serum creatinine values and median lengths and weights from different sources in the literature to evaluate several statistical models to estimate GFR in children. For enzymatic serum creatinine, we show that the simple model for uncorrected GFR (uGFR = k'L(3)/Scr, with k' = 1.32 x 10(-5)) and the BSA-corrected GFR (cGFR = kL/Scr, analogous to the Schwartz formula), with an important age-dependent adaptation for k (k = 0.0414 x 1n (Age) + 0.3018), correlate extremely well with chromium-51-ethylenediamine tetra-acetic acid ((51)Cr-EDTA) data for children between 1 month and 14 years of age. With this age-dependent modification for k, presented here, the simple bedside calculation tool derived by Schwartz can be used for screening all children for CKD. When height information is not available, the Lund-Malmö equation is an excellent alternative.

Renal function in children and adolescents with Duchenne muscular dystrophy

“…Moreover, 19 of 20 patients had mGFR values above the median reference GFR of 107.3 mL/min/ 1.73 m 2 [19]. Glomerular hyperfiltration has been associated with various diseases including diabetes mellitus, polycystic kidney disease, secondary focal segmental glomerulosclerosis, obesity, sleep apnea, cancer and blood disorders [37].…”

“…Hyperfiltration was defined as mGFR >150 mL/min/1.73 m 2 . This value is based on reference values of Pottel et al [19]: a median GFR of 107.3 mL/min/1.73 m 2 with a standard deviation of 21.5 mL/min/1.73 m 2 leads to a 97.5th percentile of 150 mL/min/1.73 m 2 .…”

“…Estimated GFR values were calculated using four Scr-based equations (Schwartz [20], Flanders Metadata [19], simple height-independent [21], Q(height) [22]), three CysC-based equations (Larsson [23], Filler [24], Zappitelli [25]) and two Scr/CysC-based equations (Zappitelli [25], Bouvet [26]). Only formulas based on enzymatic Scr and/or nephelometry were included.…”

“…Schwartz equation [20] eGFR = kL/Scr with k = 0.413 Flanders Metadata (FM) equation [19] eGFR = kL/Scr with k = 0.0414 × ln(Age) + 0.3018 Simple height-independent equation [21] eGFR = 107.3/(Scr/Q) with Q = 0.0270 × Age + 0.2329 Q(height) equation [22] eGFR = 107.3/(Scr/Q) with Q = 3.94 L, height in cm or in Q(height) equation in m; W, weight in kg, Scr, serum creatinine in mg/dL, Cys C, cystatin C in mg/L. Scr, serum creatinine; Cys C, cystatin C; HT, systolic and/or diastolic blood pressure >P95; non-dipping, systolic and/or diastolic non-dipping blood pressure profile; y/n, yes/no; ACEi, angiotensin-convertingenzyme inhibitor; d/p, deflazacort/prednisone.…”

Modification of the Schwartz equations for children increases their accuracy at eGFR > 60 mL/min/1.73 m2

“…22 In the case of children, Souza, as well as Pottel proposed a correction of the bedside Schwartz equation depending on age. 4,39 Pottel presented another concept of calculating eGFR at a known mean population creatinine concentration value for a given age. 11 It does not require knowing the averaged creatinine concentration value.…”