LDL-cholesterol and HDL-cholesterol concentrations decrease during the day

Background Homogenous assays for LDL-cholesterol (LDL-C) and HDL-cholesterol (HDL-C) are highly accurate, with little interference from triglyceride. Using these methods, we measured postprandial LDL-C and HDL-C. Earlier studies 2 suggested a postprandial decrease in LDL-C. Methods To elucidate whether LDL-C and HDL-C decrease significantly during the day, we determined daily profiles of LDL-C and HDL-C using homogeneous assays in subjects with normal coronary arteries (N; n = 10), and subjects with coronary artery disease (CAD; n = 23). Results In both groups, LDL-C and HDL-C were significantly lower from after breakfast until midnight than they were before breakfast. The next morning, they returned to baseline levels. The mean reduction in LDL-C was 0.09-0.13 mmol/L in N and 0.05-0(.)20 mmol/L in CAD, while that in HDL-C was 0(.)02-0(.)06 mmol/L in N and 0(.)00-0(.)05 mmol/L in CAD. Conclusion LDL-C and HDL-C decrease significantly over the course of the day.