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Impact of age on reference values for serum concentration of cystatin C in children
M Fischbach1, V Graff, J Terzic
1Nephrology Dialysis Transplantation Children's Unit, CHU Hautepierre, Avenue Molière, 67098 Strasbourg, France. Michel.Fischbach@chru.strasbourg.fr
Insights
Serum cystatin C (cyst C) levels are higher in infants than older children. Age-independent cyst C values in children likely emerge after one year, indicating kidney maturation.
Area of Science:
- Pediatric Nephrology
- Clinical Chemistry
- Biomarker Assessment
Background:
- Serum cystatin C (cyst C) is a proposed biomarker for glomerular filtration rate (GFR) assessment, offering potential advantages over serum creatinine.
- While cyst C reference intervals are generally considered independent of age and sex, elevated levels are noted in infants, prompting investigation into age-related stability.
- The precise age at which cyst C levels become stable and age-independent in children remains debated.
Purpose of the Study:
- To prospectively investigate the relationship between serum cystatin C levels and age in healthy children.
- To determine the age at which serum cystatin C values stabilize, indicating age independence.
- To assess the utility of cystatin C in evaluating kidney maturation in pediatric populations.
Main Methods:
- A prospective study was conducted involving 98 healthy children, with 51 participants under 18 months of age.
- Serum cystatin C (cyst C) concentrations were measured using a nephelometric method.
- Statistical analysis, including correlation, was performed to evaluate the relationship between age and cyst C levels.
Main Results:
- Infants under 18 months exhibited significantly higher mean serum cystatin C levels (0.94 +/- 0.24 mg/l) compared to older children (0.65 +/- 0.19 mg/l).
- A significant negative correlation (r(2)=0.631, P<0.01) was observed between age and serum cystatin C in infants younger than 18 months.
- The findings suggest that serum cystatin C levels decrease with age during infancy, indicating ongoing physiological changes.
Conclusions:
- Mean serum cystatin C levels are elevated in infants and decrease with age, suggesting kidney maturation.
- The age cut-off for stable, age-independent cystatin C values appears to be after one year of life.
- Further studies are needed to precisely define the age cut-off for cystatin C age independence at 18 or 36 months.
Abstract:
Recently, cystatin C (cyst C) was proposed for the assessment of glomerular filtration rate, being more accurate than creatinine determination. Reference intervals for cyst C do not vary with age and sex, like creatinine values. Elevated values of cyst C were reported for pre- and full-term infants. Nevertheless, the age cut-off for stable cyst C values i.e., age independence, remains under discussion. Therefore, we conducted a prospective study in 98 healthy children, 51 being under 18 months of age. Cyst C was determined by the nephelometric method. The infants under the age of 18 months had a higher mean serum cyst C value (0.94 +/- 0.24 mg/l) than the older children (0.65 +/- 0.19 mg/l). There was a negative correlation between age and cyst C in the infant group under the age of 18 months (r(2)=0.631, P<0.01). Our results indicate that mean serum cyst C is higher in infants than older children; the age cut-off appears over the age of 1 year of life, presumably reflecting kidney maturation. Our study does not allow accurate assessment of the age cut-off at 18 months or 36 months.