Changes in dietary protein intake has no effect on serum cystatin C levels independent of the glomerular filtration rate

Navdeep Tangri, Lesley A. Stevens, Christopher H. Schmid, Yaping Lucy Zhang, Gerald J. Beck, Tom Greene, Josef Coresh, Andrew S. Levey

Research output: Contribution to journalArticlepeer-review

Abstract

Cystatin C is being considered as a replacement for serum creatinine in the estimation of the glomerular filtration rate (GFR); however, its plasma levels might be affected by factors other than the GFR, such as protein intake. We performed a post hoc analysis of the data in the Modification of Diet in Renal Disease study, in which we compared serum creatinine and cystatin C levels in 741 patients with available estimates of protein intake at baseline prior to their randomization to diets containing various amounts of protein, and at 2 years of follow-up in 426 of these patients in whom a cystatin C measurement was available. The 503 patients in study A (GFR 25-55 ml/min per 1.73 m 2) had been assigned a low (0.58 g/kg per day) or a usual (1.3 g/kg per day) protein intake, and the 238 participants in study B (GFR 13-24 ml/min per 1.73 m 2) were assigned a very low (0.28 g/kg per day) or the low protein intake. In either study group, lowering the dietary protein intake reduced the change in creatinine, but did not have a significant change in cystatin C. Thus, in patients with moderate-to-severe chronic kidney disease, serum cystatin C unlike serum creatinine was not affected by dietary protein intake independent of changes in GFR. Hence, cystatin C may allow more accurate estimates of GFR than creatinine for patients with reduced protein intake. Further study of other non-GFR determinants of cystatin C is needed before the widespread adoption.

Original languageEnglish (US)
Pages (from-to)471-477
Number of pages7
JournalKidney international
Volume79
Issue number4
DOIs
StatePublished - Feb 2011

Keywords

  • creatinine
  • glomerular filtration rate
  • protein restriction

ASJC Scopus subject areas

  • Nephrology

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