Seasonal and biological variation of blood concentrations of total cholesterol, dehydroepiandrosterone sulfate, hemoglobin A(Ic), IgA, prolactin, andfree testosterone in healthy women

Citation
Ah. Garde et al., Seasonal and biological variation of blood concentrations of total cholesterol, dehydroepiandrosterone sulfate, hemoglobin A(Ic), IgA, prolactin, andfree testosterone in healthy women, CLIN CHEM, 46(4), 2000, pp. 551-559
Citations number
28
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Medical Research Diagnosis & Treatment
Journal title
CLINICAL CHEMISTRY
ISSN journal
0009-9147 → ACNP
Volume
46
Issue
4
Year of publication
2000
Pages
551 - 559
Database
ISI
SICI code
0009-9147(200004)46:4<551:SABVOB>2.0.ZU;2-B
Abstract
Background: Concentrations of physiological response variables fluctuate ov er time. The present study describes within-day and seasonal fluctuations f or total cholesterol, dehydroepiandrosterone sulfate (DHEA-S), hemoglobin A (1c) (HbA(1c)), IgA, prolactin, and free testosterone in blood, and estimat es within- (CVi) and between-subject (CVg) CVs for healthy women. In additi on, the index of individuality, prediction intervals, and power calculation s were derived. Methods: A total of 21 healthy female subjects participated in the study. U sing a random effects analysis of variance, we estimated CVg and total with in-subject variation (CVti), i.e., the combined within-subject and analytic al variation,from logarithmically transformed data. Analytical variation wa s subtracted from CVti to give CVi. CVi was estimated from samples taken mo nthly during 1 year (CViy), weekly during 1 month (CVim), and six times wit hin 1 day (CVid). Results: A cyclic seasonal variation was demonstrated for total cholesterol , DHEA-S, HbA(1c) prolactin, and free testosterone. Within-day variation wa s shown for prolactin and free testosterone. The overall mean values for th e group and the variability (CViy and CVg) were: 5.1 mmol/L, 5.5%, and 5.0% for total cholesterol; 6.6 mu mol/L, 7.1%, and 21% for DHEA-S; 4.3%, 2.6%, and 3.3% for HbA(1c)/hemoglobin(total); 2.1 g/L, 5.9%, and 13% for IgA; 13 6 mIU/L, 23%, and 27% for prolactin; and 5.4 pmol/L, 21%, and 29% for free testosterone. Conclusions: Collecting samples at specific hours of the day or times of th e year may reduce high biological variation. Alternatively, the number of i ndividuals may be increased and a paired study design chosen to obtain adeq uate statistical power. (C) 2000 American Association for Clinical Chemistr y.