Measurement and Estimation of Glomerular Filtration Rate in Children

Abstract

Rapid, accurate, and precise measures of kidney function are essential for the daily management of patients. While plasma and urinary clearances provide the greatest accuracy for assessing glomerular filtration rate (GFR), they are often impractical particularly for the care of children. Serum creatinine, the most commonly used endogenous marker, is simple, convenient, and practical but less accurate because of the influence of non-GFR determinants such as muscle mass which increases with age in children making growth a confounding variable in the interpretation of kidney function from creatinine alone. GFR estimating equations have been developed for adults and children to improve the accuracy of endogenous biomarkers, such as creatinine and cystatin C, by accounting for some of the non-GFR determinants thus enhancing the practitioner’s ability to assess GFR. In the steady state, when height is used as a surrogate for growth, there is a strong correlation between height/SCr and GFR. Current national guidelines recommend that the estimated GFR routinely be reported alongside the creatinine value for adults using the CKD-EPI creatinine-based formula and the updated Schwartz “bedside” formula (CKiD 2009) for children.

Relationship Between PNPLA3 rs738409 Polymorphism and Decreased Kidney Function in Children With NAFLD

“…Hence, our results might not be necessarily generalizable to other pediatric and adult populations, although these findings (as discussed previously) are also in line with those recently published in middle‐aged and elderly individuals with or without NAFLD . Finally, although we did not directly measure GFR (by plasma iohexol disappearance), we used the most widely accepted prediction formula for estimating GFR in the pediatric population (i.e., the Bedside Schwartz formula) and not the CKD epidemiology collaboration (CKD‐EPI) formula, which is used largely for estimating kidney function in adults, as this latter formula has not been validated for the use in childhood and adolescence …”

Initial collection of an inadequate 24-hour urine sample in children does not predict subsequent inadequate collections

“…Adult criteria (urine creatinine 15e20 mg/kg/24 h) were used to define an 'adequate collections in patients aged 16e17 years'. The glomerular filtration rate (GFR) was estimated using the updated bedside Schwartz formula [0.413 * height (cm)]/serum creatinine (mg/dl) [11]. Glomerular hyperfiltration was defined as a GFR !140 ml/min per 1.73 m 2 , and chronic kidney disease was defined as a GFR <90 ml/min per 1.73 m 2 [11,12].…”

Choosing the Optimal Method for Measuring Glomerular Filtration Rate in Pediatric Intensive Unit

“…Расчет СКФ по любой из указанных формул даже при высокой корреляции с истинной клубочковой фильтраци-ей не исключал одной общей проблемы: лабораторный способ определения креатинина не был стандартизован по масс-спектрометрии, поэтому ошибка в измерениях могла достигать 20% [7]. Более того, для определения концентрации креатинина использовался недостаточно точный компенсированный метод Яффе, что дополни-тельно повышало степень ошибки.…”

“…Снижение СКФ требует коррекции режима дозирования большинства препаратов, используемых в отделении интенсивной терапии [5]. Однако измере-ние СКФ часто проводится с ошибками [6], так как не все методы или формулы с достаточной точностью вос-производят необходимые измерения и вычисления [7,8]. Поэтому важно определить наиболее достоверные методы оценки и область применения той или иной формулы расчета СКФ, исключая их неправильное при-ложение.…”