title: Cystatin C improves the detection of mild renal dysfunction in older patients.
abstract: BACKGROUND
  Conventional estimates of glomerular dysfunction, including serum creatinine and creatinine clearance, are inadequate in older people. In this study we have compared the diagnostic accuracy of a novel test of kidney disease, cystatin C, against these markers in older patients with a range of renal function.
  
  
  METHODS
  Fifty-three patients (mean age 79.6 years, range 69-92 years) with a variety of medical diagnoses were recruited via outpatient clinics. Exclusion criteria included active rheumatoid disease, known current malignancy, renal replacement therapy/renal transplantation and cognitive impairment. (51)Cr-EDTA was used as the reference method against which the other markers of glomerular filtration rate were compared using regression analyses.
  
  
  RESULTS
  The best fit with glomerular filtration rate was given by Cockcroft and Gault calculated clearance (R(2) = 0.83), followed by serum cystatin C (R(2) = 0.79), serum creatinine (R(2) = 0.76) and creatinine clearance (R(2) = 0.73). The accuracy for glomerular filtration rate prediction was poor for all markers. Serum cystatin C detected nearly all patients with mild renal impairment whereas serum creatinine only detected half of these cases. Regression modelling predicted that the upper limit of normal for serum cystatin C would be exceeded as glomerular filtration rate fell below 64 mL/min/1.73 m(2), compared with 44 mL/min/1.73 m(2) for serum creatinine.
  
  
  CONCLUSIONS
  Serum cystatin C is a simple and sensitive screening test for kidney dysfunction in older people.
authors: Department of Health Care of the Older Person, East Kent Hospitals NHS Trust, Kent and Canterbury Hospital, Canterbury CT1 3NG, UK.
authors: Shelagh E
authors: SE
authors: O'Riordan
authors: Michelle C
authors: MC
authors: Webb
authors: Helen J
authors: HJ
authors: Stowe
authors: David E
authors: DE
authors: Simpson
authors: Madhu
authors: M
authors: Kandarpa
authors: Anthony J
authors: AJ
authors: Coakley
authors: David J
authors: DJ
authors: Newman
authors: Jean A
authors: JA
authors: Saunders
authors: Edmund J
authors: EJ
authors: Lamb
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D015415:Biomarkers / Q000097:blood; D003430:Cross-Sectional Studies; D055316:Cystatin C; D015891:Cystatins / Q000097:blood*; D004492:Edetic Acid; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D007674:Kidney Diseases / Q000097:blood* / Q000175:diagnosis* / Q000503:physiopathology; D008297:Male; D012016:Reference Values; D012680:Sensitivity and Specificity; D044465:White People
chemical_list: D015415:Biomarkers; C525030:CST3 protein, human; D055316:Cystatin C; D015891:Cystatins; D004492:Edetic Acid