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

George J. Schwartz, Michael F. Schneider, Paula S. Maier, Marva Moxey-Mims, Vikas R. Dharnidharka, Bradley A. Warady, Susan L. Furth, Alvaro Mũoz

Research output: Contribution to journalArticle


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 data set, 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 m 2. Further studies are needed to establish the applicability to children of normal stature and muscle mass, and higher GFR.

Original languageEnglish (US)
Pages (from-to)445-453
Number of pages9
JournalKidney international
Issue number4
StatePublished - Aug 2 2012



  • children
  • chronic kidney disease
  • clinical nephrology
  • glomerular filtration rate
  • pediatric nephrology

ASJC Scopus subject areas

  • Nephrology

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