Diurnal and seasonal variation of five carotenoids measured in human serum.
We studied within-person variation over time in serum concentrations of five carotenoids. In a diurnal study involving 33 subjects, only the 1700 h blood samples demonstrated carotenoid concentrations different from the original 0800 values. Correlations between serum concentrations of the same carotenoids drawn 1 d apart ranged from 0.93 to 0.98. In a seasonal study involving 29 subjects, no systematic trends were observed for serum concentrations of these carotenoids. Correlations between concentrations of the same carotenoids drawn 1 y apart ranged from 0.57 to 0.82. Concentrations of different carotenoids within an individual tended to be correlated with each other. Obtaining one blood sample from subjects is a relatively imprecise way to estimate their usual serum concentrations of carotenoids. If an epidemiological study was to be based on only one determination of serum carotenoids, within-person variability in serum concentrations would attenuate true regression coefficients by 4-13% and would increase the required numbers of study subjects by 19-65%.
Cantilena
L R
LR
Department of Medicine, Dartmouth Medical School, Hanover, NH 03756.
Stukel
T A
TA
Greenberg
E R
ER
Nann
S
S
Nierenberg
D W
DW
D000328:Adult; D002338:Carotenoids / Q000031:analogs & derivatives / Q000097:blood*; D002940:Circadian Rhythm; D065366:Cryptoxanthins; D005260:Female; D006801:Humans; D000077276:Lycopene; D008297:Male; D012621:Seasons; D024341:Xanthophylls; D019207:beta Carotene
D065366:Cryptoxanthins; D024341:Xanthophylls; D019207:beta Carotene; D002338:Carotenoids; C041635:alpha-carotene; D000077276:Lycopene