Lipoprotein levels fluctuate with menstrual cycle phase
MedWire News: Increases in endogenous estrogens during the menstrual cycle are associated with beneficial changes in serum lipids and lipoproteins, results of the BioCycle study show.
The findings suggest that endogenous estrogens have a similar effect on lipids as that of exogenous estrogens, say Enrique Schisterman (National Institute of Child Health and Human Development, Rockville, Maryland, USA) and co-authors in the Journal of Clinical Endocrinology and Metabolism.
The BioCycle study enrolled 259 healthy, regularly menstruating women aged between 18 and 44 years. Blood samples were obtained from the women up to eight times per cycle for up to two cycles and analyzed for levels of hormones and lipoproteins.
Levels of total cholesterol, low-density lipoprotein (LDL) cholesterol, and triglycerides were highest during the follicular phase and declined during the luteal phase, the researchers report. Meanwhile, levels of high-density lipoprotein (HDL) cholesterol increased during ovulation but did not change across other phases of the menstrual cycle.
In acute-effects models, levels of estradiol were positively associated with levels of total cholesterol and HDL cholesterol and inversely associated with LDL cholesterol and the ratio of total cholesterol to HDL cholesterol.
In persistent-effects models, estradiol was inversely associated with total cholesterol, LDL cholesterol, the ratio of total to HDL cholesterol, and triglycerides.
Commenting on their observations, Schisterman and team say that estrogen seems to have a rapid effect on increasing HDL levels while its effects on total cholesterol and LDL are not as acute.
"This study is the first to evaluate the association between endogenous estrogen and lipoproteins using multiple and longitudinal serum measures of estrogen and lipoproteins and to comprehensively consider potential impacts from other reproductive hormones," they conclude.
"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."
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By Joanna Lyford