A comparison between cystatin C, plasma creatinine and the Cockcroft and Gault formula for the estimation of glomerular filtration rate

Nephrol Dial Transplant. 2003 Oct;18(10):2024-31. doi: 10.1093/ndt/gfg349.


Background: In clinical practice, the glomerular filtration rate (GFR) is often estimated from plasma creatinine. Several studies have shown cystatin C (cys C) to be a better parameter for the diagnosis of impaired renal function. No data are available, however, on the performance of cys C in follow-up of patients, compared with creatinine. Also, comparisons of cys C with the Cockcroft and Gault (C&G) formula for estimation of GFR are few.

Methods: Plasma samples were obtained from 93 consecutive patients seen for GFR determination and from 30 patients with diabetes mellitus type 2, of whom 23 were investigated a second time after 2 years. GFR was determined with [125I]iothalamate. Plasma creatinine was determined enzymatically and the creatinine clearance calculated according to C&G. Cys C was measured with a particle-enhanced immunonephelometric method.

Results: GFR correlated with 1/cys C (r = 0.873) as well as with C&G (r = 0.876). The area under the curve (AUC) of the receiver operating curves (ROCs), a measure of diagnostic accuracy, for cys C (0.931) and C&G (0.938) were equal (P = 0.815) and both better than the creatinine AUC (0.848; P = 0.006). Bland and Altman analysis showed that the simple formula GFR = -4.32 + 80.35 x 1/cys C, derived from our data, gave more accurate (P < 0.0001) and more precise (P = 0.024) GFR estimates than obtained with the C&G formula. The day-to-day variation (biological +analytical) for cys C was small (3.1%, SD 2.51%) in diabetic patients. In the follow-up study in diabetic patients, cys C was the parameter which had the best correlation (r = 0.66) with changes in GFR.

Conclusions: Cys C shows a high correlation with GFR. With a very simple formula, cys C gives a good estimate of GFR, more accurate and precise than C&G. Because biological variation is low, cys C gives also a good assessment of GFR changes during follow-up. Cys C is the preferred endogenous parameter for GFR.

Publication types

  • Comparative Study

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Biomarkers / blood
  • Case-Control Studies
  • Child
  • Cohort Studies
  • Creatinine / blood*
  • Cystatins / blood*
  • Diabetes Mellitus, Type 2 / blood*
  • Diabetes Mellitus, Type 2 / diagnosis
  • Diabetic Nephropathies / blood*
  • Diabetic Nephropathies / diagnosis
  • Female
  • Glomerular Filtration Rate*
  • Humans
  • Kidney / physiology
  • Male
  • Middle Aged
  • Models, Biological*
  • Probability
  • ROC Curve
  • Reference Values
  • Sensitivity and Specificity
  • Severity of Illness Index


  • Biomarkers
  • Cystatins
  • Creatinine