title: Biological variability of 26 clinical chemistry analytes in elderly people.
abstract: Analytical, within-subject, and between-subject components of variation were estimated for 26 clinical chemistry analytes from duplicate analyses of 10 specimens collected from 27 healthy elderly subjects over a period of 20 weeks. Within-subject variations were similar to those generated previously by us in younger subjects. We conclude, therefore, that homeostasis is not compromised by age alone, and biological variability does not increase simply with age. All analytes except serum water had marked individuality, showing that conventional population-based reference values are of limited utility. The critical differences required for two results to be significantly (P less than or equal to 0.05) changed are not the same as those that prompt action by clinicians. Although heterogeneity of within-subject variation does exist, we believe that the critical differences generated will be useful in routine clinical decision making.
authors.affiliation: Department of Biochemical Medicine, Ninewells Hospital and Medical School, Scotland, U.K.
authors.forename: C G
authors.initials: CG
authors.lastname: Fraser
authors.forename: S T
authors.initials: ST
authors.lastname: Cummings
authors.forename: S P
authors.initials: SP
authors.lastname: Wilkinson
authors.forename: R G
authors.initials: RG
authors.lastname: Neville
authors.forename: J D
authors.initials: JD
authors.lastname: Knox
authors.forename: O
authors.initials: O
authors.lastname: Ho
authors.forename: R S
authors.initials: RS
authors.lastname: MacWalter
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000704:Analysis of Variance; D015415:Biomarkers / Q000032:analysis*; D001774:Blood Chemical Analysis; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012016:Reference Values
chemical_list: D015415:Biomarkers