title: Cystatin C, a marker for successful aging and glomerular filtration rate, is not influenced by inflammation.
abstract: BACKGROUND
  The plasma level of cystatin C is a better marker than plasma creatinine for successful aging. It has been assumed that the advantage of cystatin C is not only due to it being a better marker for glomerular filtration rate (GFR) than creatinine, but also because an inflammatory state of a patient induces a raised cystatin C level. However, the observations of an association between cystatin C level and inflammation stem from large cohort studies. The present work concerns the cystatin C levels and degree of inflammation in longitudinal studies of individual subjects without inflammation, who undergo elective surgery.
  
  
  METHODS
  Cystatin C, creatinine, and the inflammatory markers CRP, serum amyloid A (SAA), haptoglobin and orosomucoid were measured in plasma samples from 35 patients the day before elective surgery and subsequently during seven consecutive days.
  
  
  RESULTS
  Twenty patients had CRP-levels below 1 mg/L before surgery and low levels of the additional inflammatory markers. Surgery caused marked inflammation with high peak values of CRP and SAA on the second day after the operation. The cystatin C level did not change significantly during the observation period and did not correlate significantly with the level of any of the four inflammatory markers. The creatinine level was significantly reduced on the first postoperative day but reached the preoperative level towards the end of the observation period.
  
  
  CONCLUSIONS
  The inflammatory status of a patient does not influence the role of cystatin C as a marker of successful aging, nor of GFR.
authors.affiliation: Department of Clinical Chemistry, Lund University Hospital, Lund, Sweden. anders.grubb@med.lu.se
authors.forename: Anders
authors.initials: A
authors.lastname: Grubb
authors.forename: Jonas
authors.initials: J
authors.lastname: Björk
authors.forename: Ulf
authors.initials: U
authors.lastname: Nyman
authors.forename: Joanna
authors.initials: J
authors.lastname: Pollak
authors.forename: Johan
authors.initials: J
authors.lastname: Bengzon
authors.forename: Gustav
authors.initials: G
authors.lastname: Ostner
authors.forename: Veronica
authors.initials: V
authors.lastname: Lindström
mesh_terms: D000375:Aging / Q000097:blood*; D015415:Biomarkers / Q000097:blood; D002097:C-Reactive Protein / Q000378:metabolism; D003404:Creatinine / Q000097:blood; D055316:Cystatin C / Q000097:blood*; D005919:Glomerular Filtration Rate / Q000502:physiology*; D006801:Humans; D007249:Inflammation / Q000097:blood*; D000685:Serum Amyloid A Protein / Q000378:metabolism
chemical_list: D015415:Biomarkers; C525030:CST3 protein, human; D055316:Cystatin C; D000685:Serum Amyloid A Protein; D002097:C-Reactive Protein; D003404:Creatinine