Low diurnal variability of apolipoprotein A1, apolipoprotein B and apolipoprotein B/apolipoprotein A1 ratio during normal sleep and after an acute shift of sleep

Objective: The aim of this study was to study the diurnal variation of the cardiovascular risk markers apolipoprotein A1 and B and apo B/apo A1 ratio. Design and methods: We have studied the diumal variation of apolipoprotein A1, apolipoprotein B and apo B/apo A1 ratio during night sleep and the day sleep conditions in seven healthy volunteers (age 22-32 yr). Samples were collected every hour to evaluate the effect of different sampling times on the test results. Results: The lowest diumal coefficient of variation (CV) was observed for the apo B/apo A1 ratio, which usually was below 2% but also apolipoprotein A1, apolipoprotein B showed low CV. There were no significant differences between nightsleep and daysleep, for any of the studied markers. Conclusion: Even if there was a diumal variation for these markers, the variation was very low. Thus, sampling does not have to be restricted to certain times of the day. (C) 2008 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.