Methods of assessing renal function. Pediatr Nephrol

Department of Pediatrics, Children's Hospital, London Health Science Centre, University of Western Ontario, 800 Commissioners Road East, London, Ontario, Canada, N6A 5W9, .
Pediatric Nephrology (Impact Factor: 2.86). 02/2013; 29(2). DOI: 10.1007/s00467-013-2426-7
Source: PubMed


Accurate assessment of renal function is critical for appropriate drug dosing of renally excreted compounds. Glomerular filtration rate (GFR) is considered the best marker of kidney function. Inulin clearance forms the gold standard for measuring GFR, both in adults and in children. The method is invasive, cumbersome, and smaller children require urinary catheterization for accurate timed urine collections. Nuclear medicine methods replaced inulin clearance in the 1970s after (51)Cr EDTA clearance was introduced. Inulin has no plasma protein binding, whereas all commonly used radioisotopes have a small amount of plasma protein binding that leads to lower values. Only iohexol does not have significant plasma protein binding. The underestimation due to plasma protein binding is partially offset by overestimation due to the use of non-compartmental pharmacokinetic modeling of the plasma disappearance of the radioisotope. The problem could be overcome with a urinary nuclear medicine clearance method, but these have not been validated in children. Endogenous markers of GFR include serum creatinine and low molecular weight proteins such as cystatin C and beta-trace protein. Of these, estimation of GFR using cystatin C appears to be the most promising, although its accuracy in pregnancy and in the neonatal period may be limited.

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Available from: Guido Filler, Sep 30, 2015
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    • ") . A specific and unresolved normalization problem is related to determination of children ' s GFR , as discussed in several stud - ies ( e . g . reviewed by Filler et al . , 2014"
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    • "Iohexol, a nonradiolabeled contrast agent, is also currently used as a measure of GFR by calculating its plasma clearance after intravenous bolus injection. Iohexol clearance is a good alternative to inulin and showed a high degree of reproducibility over a wide range of renal function [77]. In renal transplant recipients, however, the performance of the GFR equation is suboptimal and it seems that tubular dysfunction contributes to this disagreement in measured and estimated GFR [78]. "
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