Improved equations estimating GFR in children with chronic kidney disease using an immunonephelometric determination of cystatin C

Kidney Int. 2012 Aug;82(4):445-53. doi: 10.1038/ki.2012.169.


The Chronic Kidney Disease in Children study is a cohort of about 600 children with chronic kidney disease (CKD) in the United States and Canada. The independent variable for our observations was a measurement of glomerular filtration rate(GFR) by iohexol disappearance (iGFR) at the first two visits 1 year apart and during alternate years thereafter. In a previous report, we had developed GFR estimating equations utilizing serum creatinine, blood urea nitrogen, height, gender, and cystatin C measured by an immunoturbidimetric method; however, the correlation coefficient of cystatin C and GFR(0.69) was less robust than expected. Therefore, 495 samples were re-assayed using immunonephelometry. The reciprocal of immunonephelometric cystatin C was as well correlated with iGFR as was height/serum creatinine (both 0.88). We developed a new GFR estimating equation using a random 2/3 of 965 person-visits and applied it to the remaining 1/3 as a validation data set. In the validation dataset, the correlation of the estimated GFR with iGFR was 0.92 with high precision and no bias; 91 and 45% of eGFR values were within 30 and 10% of iGFR, respectively. This equation works well in children with CKD in a range of GFR from 15 to 75 ml/min per 1.73 m2. Further studies are needed to establish the applicability to children of normal stature and muscle mass, and higher GFR.

Publication types

  • Multicenter Study
  • Research Support, N.I.H., Extramural
  • Validation Study

MeSH terms

  • Adolescent
  • Biomarkers / blood
  • Blood Urea Nitrogen
  • Body Height
  • Canada
  • Child
  • Child, Preschool
  • Cohort Studies
  • Contrast Media
  • Creatinine / blood
  • Cystatin C / blood*
  • Female
  • Glomerular Filtration Rate*
  • Humans
  • Immunoassay*
  • Infant
  • Iohexol
  • Kidney / metabolism
  • Kidney / physiopathology*
  • Linear Models
  • Male
  • Models, Biological*
  • Multivariate Analysis
  • Nephelometry and Turbidimetry*
  • Predictive Value of Tests
  • Renal Insufficiency, Chronic / blood
  • Renal Insufficiency, Chronic / diagnosis*
  • Renal Insufficiency, Chronic / physiopathology
  • Reproducibility of Results
  • Time Factors
  • United States


  • Biomarkers
  • CST3 protein, human
  • Contrast Media
  • Cystatin C
  • Iohexol
  • Creatinine