Plasma carnitine in women. Effects of the menstrual cycle and of oral contraceptives.

The plasma concentrations of carnitine were determined in a group of 35 women and 35 men admitted to a clinic, and in another group of 18 women during their menstrual cycle. The values found for the women (45.1 +/- 2.6 nmol/ml of free carnitine and 59.1 +/- 2.8 nmol/ml of total carnitine) were not significantly different from the values obtained in men (respectively 42.4 +/- 1.7 and 55.5 +/- 1.9 nmol/ml). No direct relationship between the free or total carnitine concentrations and the concentrations of circulating lipids could be demonstrated. During the menstrual cycle the plasma concentrations of free and total carnitine remained unchanged. Intake of oral contraceptives caused an elevation in blood triacylglycerols and decreases in the levels of luteinizing hormone, follicle-stimulating hormone, and free and total carnitine.