Expressing glomerular filtration rate in children

Abstract

We have reviewed the studies that provide the current standards of reference for glomerular filtration rate (GFR) in normal children from 14 days to 12 years of postnatal age. These standards currently are presented as ml/min per 1.73 m2, i.e., adjusted to average adult body surface area. Children from birth to 1 year of age have adjusted values below the adult range, making comparisons of observed to reference values difficult. Currently, there is no accepted way of obtaining reference values that vary smoothly with age. An analysis of the absolute GFR values in normal children taken from published studies led to an equation that estimates average GFR in relation to weight and term-adjusted age from -2 months (7 months gestational age) to 12 years in children at least 14 days post delivery. When these data are transformed to percentage of normal (% nl) for age and weight (i.e., percentage of the estimated average), it is possible to describe approximate apparent lower limits of normal GFR as is now done for adults and older children. For children with loss of renal mass, GFR expressed as % nl for age and weight provides a convenient standardization which has several useful applications. First, results expressed as % nl for children of different ages, particularly under 1 year of age, can be combined with those of older children for summary purposes. Second, the course of GFR measured serially in children is more appropriately described using this method for expressing GFR. Reporting GFR in absolute values is also useful, particularly in patients whose body mass is significantly distorted or whose absolute GFR is low.

Permeation of macromolecules into the renal glomerular basement membrane and capture by the tubules

“…Normally, children will not reach a GFR of 100 until 1 y of age [Table S2, which also reports effective renal plasma flow (ERPF) measured as clearance of para-aminohippuric acid (PAH) (22) and serum creatinine levels (23)] (see also ref. 24). This interpretation of the data does not exclude the possibility that the slit-diaphragm acts as a molecular sieve, but it questions whether this action is required.…”

Postnatal Maturation of the Glomerular Filtration Rate in Conventional Growing Piglets As Potential Juvenile Animal Model for Preclinical Pharmaceutical Research

“…The increasing GFR in those studies was similar to the trends observed in the current study. In humans, the GFR is 2–4 mL/min/1.73 m 2 at birth, increases rapidly to 39–47 mL/min/1.73 m 2 during the first 2 weeks of life, continues rising to 58–103 mL/min/m 2 during the first year of life and reaches adult values (127 mL/min/1.73 m 2 ) at the age of 2 years (Guignard et al, 1975; Heilbron et al, 1991). The age correlations between humans and pigs proposed by Gad (2007) were considered here to compare the GFR between humans and piglets, namely neonate (human: 0–28 days, pig: 0–15 days), infant (human: 1–23 months, pig: 2–4 weeks), child (human: 2–12 years, pig: 4–14 weeks) and adolescent (human: 12–16 years, pig: 4–6 months).…”

Measurement and Estimation of Glomerular Filtration Rate in Children

“…9 In children, there is also a maturational increase in GFR beginning at birth when it is very low (~20 mL/min/1.73 m 2 ) and ultimately culminating in the adult level of ~120 mL/min/1.73 m 2 by approximately 2 years of age. 10 …”