Diurnal changes in serum triglycerides as related to changes in lipolytic enzymes, lipoproteins and hormones in patients with primary endogenous hypertriglyceridaemia on a carbohydrate-rich diet.

Parameters of diurnal triglyceride (TG) metabolism were investigated in 5 subjects with primary endogenous hypertriglyceridaemia and compared with those of normal subjects studied previously. The patients were in a steady state on a carbohydrate-rich diet (meals at 9.00, 13.00 and 17.00 h). Serum TG showed a wavelike pattern with a maximum at around 17.00 h. Post-heparin lipoprotein lipase (LPL) activity in the fasting state was not different from that in normals, but failed to show the normal increase in the fed state (16.30 h). This was due to the inability of patients to increase their adipose tissue (AT)-LPL activity in the course of the day. AT-LPL activity was throughout the day lower than in normal subjects. Skeletal muscle LPL activity was low and showed no diurnal change, equalling our findings in normal subjects. Low density lipoprotein cholesterol and high density lipoprotein (HDL) cholesterol concentrations showed no diurnal change. However, HDL phospholipids increased significantly in the course of the day.