Estimation of the glomerular filtration rate in children: which algorithm should be used?

Abstract

Glomerular filtration rate (GFR) in children can be estimated by the formula GFR=k x BH/Pcr (where BH is body height in centimetres and Pcr is the plasma creatinine concentration in micromoles per litre). For k, several values have been reported: k=38 (Counahan), k=40 (Morris) and k=48.7 (Schwartz). In this study the predictive performance of these formulae was compared with that of newly developed formulae. GFR measurements based on inulin concentration time curves were divided into an index (n=58) and a validation data set (n=48). In the index data set a value for k was derived by application of nonlinear mixed-effect modelling. This approach was also used to develop a formula that better explained the relationship between patient factors and GFR. Bias and precision of all formulae were calculated for the validation data set. In the index data set a value of 41.2 was found for k, which was close to the value k=40 (Morris). Both formulae estimated GFR well (bias <5%; precision 25%). Further modelling of the relationship between patient factors and GFR did not improve the predictive performance. In our hospital GFR was best estimated by the formula with k=40 and k=41.2. It is recommended that the optimal value for k be assessed locally.

Determinants of eGFR at start of renal replacement therapy in paediatric patients

“…A possible explanation for this could be related to the use of different K values for adolescent males in the original Schwartz formula. The use of different formulas for males and females has been found appropriate in some studies [3,9,16] although not in others [17][18][19]. When we used a single K value as suggested in the revised Schwartz and Counahan formula, the gender differences disappeared.…”

Oxidative stress, inflammation and early cardiovascular damage in children with chronic renal failure

“…The mean glomerular filtration rate (GFR) of nondialysis CRF children was 13.4±3.2 (range 11.0-21.4) ml/min. Estimated GFR (eGFR) values were calculated for all CRF children using the Schwartz formula (k×height/plasma creatinine) [17]. Systolic blood pressure (SBP) and diastolic blood pressure (DBP) were measured upon admission to hospital by auscultation with an aneroid sphygmomanometer with the patient in the sitting position and an appropriately sized cuff.…”

Mycophenolate mofetil versus cyclosporine for remission maintenance in nephrotic syndrome

“…The GFR was calculated using an adapted Schwartz formula [25,26]. Serum lipids [cholesterol, triglycerides, low-density lipoprotein-cholesterol (LDL) and high-density lipoprotein cholesterol (HDL)] were measured at study entry and after 1 year.…”