[Postural change and within-day variation in total cholesterol and high-density lipoprotein-cholesterol levels]

To clarify whether the effect of the postural change on lipid levels can be corrected after the adjustment of albumin levels, and if so, whether there is within-day variation in corrected lipid levels, we measured total cholesterol (TC), high-density lipoprotein-cholesterol (HDL-C), and albumin levels before and after 60 min of the supine posture in 6 volunteers. We also measured the same variables before and after meals and at midnight in 30 inpatients with diabetes mellitus. We found that TC levels decreased by -7.7 +/- 2.7% (p < 0.005), and HDL-C by -5.8 +/- 5.3% (p < 0.05) after 60 min of the supine posture. The decreases disappeared after the adjustment of albumin to the baseline levels (TC; -0.2 +/- 1.0%, HDL-C; -1.7 +/- 4.2%, not significant). The within-day variation decreased from 10.9 +/- 4.9% to 5.8 +/- 2.2% in TC, and from 13.8 +/- 4.7% to 9.5 +/- 3.9% in HDL-C after the albumin adjustment. Corrected TC levels were, however, significantly lower after breakfast through at midnight than those before breakfast. This study indicates that the postural changes in lipid levels can be corrected after the adjustment of albumin levels, and that there is within-day variation in corrected TC levels. These findings suggest that the timing of sampling should be standardized for TC measurement in the management of diabetes mellitus with hypercholesterolemia.