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.

Estimates of biological variation in routinely measured biochemical analytes in clinically healthy dogs

“…Our data indicate that high individuality is present for many routinely measured biochemical analytes in dogs. This is consistent with the human medical literature, where many analytes have high degrees of individuality on serial determination . Using criteria established by Fraser and others, an index of individuality < 0.7 (when calculated as CV G /(CV A 2 +CV I 2 ) 1/2 , as performed in this study) indicates that comparison of an individual to a population‐based reference interval is appropriate, whereas an index of > 1.7 indicates that a population‐based reference interval is of limited utility .…”

Alanine aminotransferase as a marker of non‐alcoholic fatty liver disease in relation to type 2 diabetes mellitus and cardiovascular disease

“…It is therefore strongly advisable not to determine ALT activity in frozen samples, as a falsely decreased ALT activity may be found. Day‐to‐day variations of 10–30% have been observed 29. Moreover, significant diurnal variations have been reported in both healthy subjects and in patients with chronic liver disease (CLD), necessitating standardised blood sampling times when comparing enzyme values in clinical practice and research 30.…”

Biological variation of thromboelastrography variables in 10 clinically healthy horses

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