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Determination of cystatin C reference interval for children in Croatia
Vlasta Cigula Kurajica1, Željka Vogrinc1, Ana Turčić1
1Department for Laboratory Diagnostics, University Hospital Centre Zagreb, Zagreb, Croatia.
Insights
This study establishes crucial Cystatin C reference intervals for children, vital for early kidney damage detection. These findings confirm Cystatin C levels normalize after age one, supporting its use in pediatric eGFR calculations.
Area of Science:
- Pediatric Nephrology
- Clinical Chemistry
- Biomarker Research
Background:
- Cystatin C is a recognized early indicator of renal function impairment.
- Establishing age-specific reference intervals for Cystatin C in children is essential for accurate clinical interpretation.
- Manufacturer-provided reference intervals may not be suitable for pediatric populations.
Purpose of the Study:
- To determine the reference intervals for Cystatin C in a pediatric population (0-18 years).
- To assess the applicability of the Schwartz's formula for estimating glomerular filtration rate (eGFR) using Cystatin C in children.
- To provide essential data for the early detection of kidney damage in children.
Main Methods:
- Cystatin C was measured using an immunoturbidimetric method, and creatinine using an enzymatic method.
- Reference intervals were established following CLSI C28-A3 guidelines, employing robust and nonparametric percentile methods.
- The Schwartz's formula was utilized to calculate estimated glomerular filtration rate (eGFR) from Cystatin C levels.
Main Results:
- Established Cystatin C reference intervals for children aged 1-18 years (0.61-1.08 mg/L) and 0-1 years (0.60-1.49 mg/L).
- No significant sex-based differences in Cystatin C levels were observed in children over one year old.
- Mean eGFR values were 76 mL/min/1.73m² for males and 83 mL/min/1.73m² for females.
Conclusions:
- Defined age-specific Cystatin C reference intervals for the Croatian pediatric population.
- Cystatin C concentrations in children attain adult levels by the first year of age.
- The Schwartz's formula is validated for eGFR calculation in pediatric patients using Cystatin C.
Introduction:
Cystatin C is considered an early marker of kidney damage. The aim was to determine the reference interval in children since this information was not available from the test manufacturer.
Materials And Methods:
Included were children aged 0 to 18 years undergoing routine check without history of any renal disease. Cystatin C was measured by the immunoturbidimetric method, and creatinine by the enzymatic method on a Cobas c501 analyzer (Roche Diagnostics, Manheim, Germany). Reference intervals were determined according to the CLSI C28-A3 guidelines using a robust method and a nonparametric percentile method, depending on the sample size. The Schwartz's formula was applied to estimate glomerular filtration (eGFR) from cystatin C.
Results:
The cystatin C reference interval for children aged 1-18 years (N = 204, median 8 years) was from 0.61 mg/L (90% CI: 0.53 to 0.64) to 1.08 mg/L (90% CI: 1.07 to 1.14). Differences according to sex were not found. For children aged 0-1 years (N = 29, median 5 months), the reference interval was from 0.60 mg/L (90% CI: 0.48 to 0.72) to 1.49 mg/L (90% CI: 1.36 to 1.61). The sample size was too small to test the difference according to sex. The eGFR was 76 (70-88) mL/min/1.73m2 for males and 83 (74-92) mL/min/1.73m2 for females.
Conclusion:
The cystatin C reference intervals for Croatian pediatric population according to age were determined. The cystatin C concentrations in children reach adulthood values after the first year. The cystatin C Schwartz's formula is applicable for eGFR calculation in children.
