Cholesterolwaarden variëren gedurende de menstruele cyclus

Chapel Hill, NC - Cholesterol levels in women vary significantly across the different phases of the menstrual cycle, a new study has shown [1]. The results, according to investigators, have practical implications as well as implications for future clinical trials that include women.

"Cyclic variations in lipoprotein-cholesterol levels observed in the present study may have clinical implications regarding the appropriate timing of lipoprotein-cholesterol measurement during the cycle and may need to be accounted for in the design and interpretation of studies in women of reproductive age," write lead investigator Dr Sunni Mumford (University of North Carolina, Chapel Hill) and colleagues in a report published online June 9, 2010 in the Journal of Clinical Endocrinology and Metabolism.

In their paper, the authors point out that hormone therapy in the Women's Health Initiative (WHI) and Heart and Estrogen/Progestin Replacement Study (HERS) improved lipoprotein profiles, even though it was ultimately associated with increased rates of cardiovascular disease. With exogenous estrogen altering the lipid profile, the hypothesis entering this analysis was that endogenous estrogens might also have a similar effect on lipids.

The researchers assessed the total cholesterol, HDL cholesterol, LDL cholesterol, and triglycerides of 259 healthy, premenopausal women currently not taking oral contraceptives or other medications. Among these women, total cholesterol, LDL cholesterol, and triglycerides were highest during the follicular phase of the cycle and declined during the luteal phase. LDL cholesterol, for example, declined 4.9% from the midfollicular phase to the midluteal phase of the menstrual cycle, while total cholesterol declined 3.0%. HDL cholesterol levels were highest during ovulation but did not change during the other phases of the cycle.

When assessed during the follicular phase of the cycle, 14% of women had high total-cholesterol levels, whereas 8% of women measured during the late luteal phase had total-cholesterol levels considered high. Results were similar when assessing women with high LDL-cholesterol levels.

"Although the total-cholesterol and LDL changes observed were modest, only 5% to 8%, on average, women [crossed] between clinical boundaries of acceptable levels," write Mumford and colleagues. "While treatment decisions regarding the lipid profile may still require repeated samples above the recommended level, standardizing the timing of lipid measurements may improve the interpretability of results and consequently reduce the overall number of tests."

In a linear-effects model testing acute-phase associations, meaning between measurements taken on the same day, the group showed that estradiol was positively associated with HDL cholesterol and inversely associated with total and LDL cholesterol and with triglycerides.

1. Mumford SL, Schisterman EF, Siega-Riz AM, et al. A longitudinal study of serum lipoproteins in relation to endogenous reproductive hormones during the menstrual cycle: Findings from the BioCycle study. J Clin Endocrinol Metab 2010; DOI: 10.1210/jc.2010-0109.