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
    • "Of these, nephron formation and recruitment associated with development may have the most profound effect[6]. Monitoring renal function in neonates is essential for determining the accurate dosage of kidney-excreted medications[7,8]. Very premature babies present particular challenges because the nephrogenesis that would normally continue to the 36th week of gestation in utero is interrupted, or at least altered, with the child's delivery[9]. "
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    ABSTRACT: Purpose of review: This article answers the question of whether creatinine is the best biomarker for monitoring neonatal glomerular filtration rate (GFR) in view of recent advances in measuring neonatal renal function. Recent findings: We rely largely on serum creatinine for the estimation of GFR in the newborn, even though creatinine is freely exchanged through the placenta. During the first few days of life, the serum creatinine reflects maternal renal function or the maternal creatinine. Back filtration of creatinine in preterm newborns is also a serious limitation. This review summarizes current knowledge on the prenatal and postnatal handling of creatinine as well as that of other, more novel biomarkers of GFR, such as cystatin C (CysC) and β-trace protein (BTP). Only small amounts of CysC cross the placenta, whereas BTP does not cross the placenta at all. However, BTP measurements are not widely available. Recent studies on renal volumetry are also discussed. Summary: Currently, CysC may be the most suitable marker of neonatal renal function, but its availability is still limited, it is more costly, and the best method of reporting acute kidney injury and neonatal estimated GFR remains to be established.
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    • "The ontogeny of drug disposition is considerable in the neonatal period and is largely due to the formation and recruitment of nephrons that comprise the acquisition of renal function during development [5]. It is therefore essential to monitor renal function in neonates to accurately dose kidneyexcreted medications [6] [7]. Premature infants, however, present particular challenges because the nephrogenesis that would normally continue to "
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    ABSTRACT: Measuring renal function in neonates and small infants is important to ensure that drugs are safely dosed and to detect acute kidney injuries early on. Serum creatinine (Cr) remains the most widely used marker, but its shortcomings are particularly important in neonates. For example, neonatal Cr largely depends on maternal renal function for at least the first 72. h of life. Novel approaches for assessing neonatal renal function include cystatin C and beta-trace protein. Another way to assess renal function is to measure renal volume by ultrasound. Although this approach may assess neonatal nephron endowment, it is insensitive to the postnatal adaptation of renal function in term and preterm neonates. The purpose of this review is to summarize what is known about measuring renal function in term and preterm newborns, and to summarize existing knowledge gaps, including a description of steps to take to close these gaps.
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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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