title: Comparison between Cystatin C- and Creatinine-Estimated Glomerular Filtration Rate in Cardiology Patients.
abstract: OBJECTIVE
  Estimation of the glomerular filtration rate (GFR) is essential for identification, evaluation and risk prediction in patients with kidney disease. Estimated GFR (eGFR) is also needed for the correct dosing of drugs eliminated by the kidneys and to identify high-risk individuals in whom coronary angiography or other procedures may lead to kidney failure. Both cystatin C and creatinine are used for the determination of GFR, and we aimed to investigate if eGFR by the two methods differ in cardiology patients.
  
  
  METHODS
  We compared cystatin C and creatinine (CKD-EPI) eGFR calculated from the same request from a cardiology outpatient unit (n = 2,716), a cardiology ward (n = 980), a coronary care unit (n = 1,464), and an advanced coronary care unit (n = 518) in an observational, cross-sectional study.
  
  
  RESULTS
  The median creatinine eGFR results are approximately 10 ml/min/1.73 m(2) higher than the median cystatin C eGFR that is up to 90 ml/min/1.73 m(2), irrespective of the level of care. Creatinine eGFR resulted in a less advanced eGFR category in the majority of patients with a cystatin C eGFR <60 ml/min/1.73 m(2).
  
  
  CONCLUSIONS
  Our study demonstrates a difference between creatinine and cystatin C eGFR in cardiology patients. It is important to be aware of which marker is used for the reported eGFR to minimize erroneous interpretations of the test results, as this could lead to under- or overmedication. Further studies are needed to determine the best method of estimating the GFR in cardiology units.
authors.affiliation: Department of Medical Sciences, University Hospital, Uppsala University, Uppsala, Sweden ; Uppsala Clinical Research Center, Uppsala, Sweden ; Duke Clinical Research Institute, Durham, N.C., USA.
authors.forename: Axel
authors.initials: A
authors.lastname: Åkerblom
authors.affiliation: Department of Medical Sciences, University Hospital, Uppsala University, Uppsala, Sweden.
authors.forename: Johanna
authors.initials: J
authors.lastname: Helmersson-Karlqvist
authors.affiliation: Department of Medical Sciences, University Hospital, Uppsala University, Uppsala, Sweden.
authors.forename: Mats
authors.initials: M
authors.lastname: Flodin
authors.affiliation: Department of Medical Sciences, University Hospital, Uppsala University, Uppsala, Sweden.
authors.forename: Anders
authors.initials: A
authors.lastname: Larsson
keywords: CKD-EPI; Creatinine; Cystatin C; Glomerular filtration rate; Heart; Kidney; Sweden