Diurnal variation in lipoprotein-associated phospholipase A(2) (Lp-PLA(2))

ObjectivesThe aim of our study was to determine the diurnal variation of lipoprotein-associated phospholipase A₂ (Lp-PLA₂), an arterial-specific inflammatory enzyme implicated in the formation of vulnerable, rupture-prone plaque that can identify individuals at high risk for cardiovascular disease. Presently, the diurnal variation of Lp-PLA₂ is not known.Design and MethodsTen men and 8 women (age range: 22–76 years) had a blood sample taken every 4 h over a 24-hour time period. Samples were analyzed for both Lp-PLA₂ mass and activity.ResultsThe mean coefficient of variation (CV) for Lp-PLA₂ mass was 5.9% (ranges from 2.5 to 9.4%) for the 18 subjects. Similarly, the mean CV for Lp-PLA₂ activity was 3.7% (ranges from 1.2 to 6.8%). There were no significant correlations between CV and any of the subject characteristics.ConclusionsThe diurnal variation of Lp-PLA₂ mass and activity is similar to that of well accepted lipoprotein risk factors. With the relatively low diurnal variability, there does not appear to be a need to make sure serial measurements of Lp-PLA₂ mass and activity are taken at the same time of the day.