Article Text

Download PDFPDF
Does adjustment of GFR to extracellular fluid volume improve the clinical utility of cystatin C?


BACKGROUND Cystatin C measurement has been proposed as a replacement for creatinine as a serum measure of glomerular filtration rate (GFR). It has also been suggested that GFR itself should be adjusted to the extracellular fluid volume (ECV) of a child rather than the body surface area (BSA).

AIMS To assess the potential of cystatin C compared to serum creatinine in assessing GFR and to establish whether adjustment of GFR to ECV rather than BSA affects the potential usefulness of cystatin C.

METHODS Cystatin C and plasma creatinine were measured in 64 paediatric patients undergoing 7751Cr-EDTA GFR measurements over a six month period.

RESULTS 1/cystatin C concentrations were more closely related to GFR (median 98 ml/min/1.73 m2, range 8–172) after adjustment for patient BSA (r = 0.81 versusr = 0.44). 1/Creatinine concentrations appeared to be an inferior estimate of BSA adjusted GFR (r = 0.41), even following the use of the Schwartz formula (r = 0.37). Bland Altman statistics showed cystatin C could still only predict 95% of GFR values to within ±41 ml/min/1.73 m2 of the51Cr-EDTA method. The relation between GFR and 1/cystatin C was not improved by adjusting 51Cr-EDTA GFR to ECV rather than BSA (r = 0.76 versusr = 0.81).

CONCLUSIONS Cystatin C appears superior to serum creatinine in paediatric subjects although its performance is unlikely to supplant 51Cr-EDTA GFR measurement. This performance is not being underestimated because of adjusting GFR to BSA rather than ECV.

  • cystatin C
  • glomerular filtration rate

Statistics from

Request Permissions

If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.