title: Diagnostic efficiency of cystatin C and serum creatinine as markers of reduced glomerular filtration rate in the elderly.
abstract: This is a secondary analysis of data from a cross-sectional study to evaluate the diagnostic efficiency of cystatin C as a marker of the glomerular filtration rate in the elderly. Thirty patients (15 male, 15 female, mean age 75.4 +/- 7.1 years) attending a geriatric ward were enrolled. Exclusion criteria were previously diagnosed renal disease, dementia and heart failure (NYHA III or IV). Cystatin C in serum was determined by a particle-enhanced turbidimetric assay. Inulin clearance was assessed using a single-shot method. Also, Cockcroft-Gault formula was calculated. Twelve patients had a reduced glomerular filtration rate (<70 ml/min/ 1.73 m2). The mean values were 88.4 micromol/l (+/- 27.7) for serum creatinine, 1.57 mg/l (+/- 0.34) for cystatin C and 88.7 ml/min/1.73 m2 (+/- 34.6) for inulin clearance. Maximum efficiency was 0.73 for serum creatinine (cut-off limit 82 micromol/l), 0.67 for cystatin C (cut-off limit 1.63 mg/l) and 0.8 for Cockcroft and Gault estimation (cut-off limit 54 ml/min/1.73 m2). A receiver operating characteristics (ROC) analysis did not show any differences between the various methods. Therefore, cystatin C in serum may not improve the diagnostic efficiency in detecting a reduced glomerular filtration rate in the elderly. Furthermore, normal ranges for serum creatinine in the elderly might need to be adjusted.
authors.affiliation: IV. Medizinische Klinik, Geriatrie, Universität Heidelberg, Klinikum Mannheim, Mannheim, Germany. heinrich.burkhardt@med.ma.uni-heidelberg.de
authors.forename: Heinrich
authors.initials: H
authors.lastname: Burkhardt
authors.forename: Gero
authors.initials: G
authors.lastname: Bojarsky
authors.forename: Rainer
authors.initials: R
authors.lastname: Gladisch
mesh_terms: D000367:Age Factors; D000368:Aged; D015415:Biomarkers / Q000097:blood; D003404:Creatinine / Q000097:blood*; D003430:Cross-Sectional Studies; D055316:Cystatin C; D015891:Cystatins / Q000097:blood*; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D007444:Inulin / Q000097:blood; D008297:Male; D008657:Metabolic Clearance Rate; D009391:Nephelometry and Turbidimetry / Q000379:methods; D012372:ROC Curve; D012680:Sensitivity and Specificity
chemical_list: D015415:Biomarkers; C525030:CST3 protein, human; D055316:Cystatin C; D015891:Cystatins; D007444:Inulin; D003404:Creatinine