Cystatin C in newborns: a promising renal biomarker in search for standardization and validation

Abstract

Objective Neonatologists still commonly use creatinine as a proxy for renal clearance, despite issues related to neonatal (patho)physiology and methodology (assay variability). Cystatin C (CysC) has been suggested to be a more reliable biomarker, but assay related differences have also been reported in children and adults. We are unaware of any review on the assay related impact on CysC reference values in newborns. Methods A structured literature search was performed on published CysC values in (pre)term neonates. Results The extensive range (>5-fold) in serum CysC observations in neonates in part relates to the fact that CysC concentrations are higher at birth with subsequent decrease and that CysC concentrations are higher in preterm compared to term neonates. The CysC assay matters while disease characteristics also affect CysC values, but not always in the predicted direction. Conclusions Similar to creatinine, the extensive CysC range in neonates is only in part explained by renal (patho)physiology. Its applicability in neonatal medicine can be further improved by use of assay specific reference values, adapted to neonatal renal physiology (e.g. weight, age) and should be compared to a gold standard such as inulin clearance.

Investigation of urine proteome of preterm newborns with respiratory pathologies

“…The role of some core proteins in the kidney and urinary tract function of adults and children was previously discussed [33][34][35][36][37][38]. EGF participates in renal development, a postnatal rise in renal EGF content and urinary EGF excretion suggests a role of EGF in renal maturation [38].…”

“…Cystatin C is mainly used as a biomarker of kidney function and glomerular filtration rate (GFR) [34][35][36] and its level was shown to be higher in preterm as compared to term neonates [33]. Retinol-binding protein is a low molecular weight protein of 21 kDa that transports retinol from the liver to peripheral tissues.…”

Prediction of urine volume soon after birth using serum cystatin C

“…Recent studies, however, have shown that S-CysC is more useful biomarker for renal function than S-Cr even in children including neonates [23][24][25]. Furthermore, unlike Cr, CysC does not cross the placenta; therefore, the CysC levels may reflect renal function of the neonates even at the first day of life [26,27] though only few studies have examined S-CysC levels in this period [5][6][7].…”

“…In adults, serum cystatin C (S-CysC), which is less influenced by extrarenal factors, is being used as a sensitive biomarker for renal function [3,4]. The same has not been extensively studied in the early neonatal period [5][6][7].…”

Цистатин С І Хронічна Хвороба Нирок У Дітей

“…Allegaert і співавтори у пошуках стандарти-зації і валідації перспективного біомаркера нирок цистатину С визначили, що його застосування в неонатальній медицині може бути додатково по-кращено за рахунок використання конкретних контрольних значень, адаптованих до неонаталь-ної ниркової фізіології [3].…”