Many changes are brought about by shifting levels of hormones associated with menopause in women. One of them, according to a new research, is deterioration in the quality of cholesterol carriers, which increases womens’ risk of heart disease.
The research challenges previously held beliefs about cholesterol. "Higher levels of HDL, or what we know as 'good cholesterol,' may not always be protective, as we have thought before,"said lead investigator Samar R. El Khoudary, assistant professor in Pitt Public Health's Department of Epidemiology, in a press release.
According to Dr. El Khoudary, it is not the level of LDL, or “bad cholesterol” which is the marker for cholesterol levels but quality of cholesterol carriers which determine if cholesterol poses a health risk for the individual or not.
"We found that lower levels of estradiol, one of the main hormonal changes that mark menopause, are associated with low-quality cholesterol carriers, which have been found to predict risk for heart disease," she said. "Our results suggest that there may be value in using advanced testing methods to evaluate changes in cholesterol carriers' quality in women early in menopause so that doctors can recommend appropriate diet and lifestyle changes."
The research carried out at University of Pittsburgh Graduate School of Public Health used an advanced detection method called nuclear magnetic resonance spectroscopy to identify the type of blood cholesterol and how it affects menopausal women. The results, published in the July issue of the Journal of Lipid Research, was supported by National Institutes of Health (NIH).
Low density lipoprotein (LDL) and high-density lipoprotein (HDL) are two types of lipoproteins that carry cholesterol through the bloodstream. LDL is called the “bad” cholesterol because it contributes to plaque, a thick, hard deposit that can clog arteries and make them less flexible.
HDL is considered “good” cholesterol because it helps scavenge and remove LDL cholesterol from the arteries. Most conventional blood tests only show the amount of LDL and HDL and not their characteristics like size and number, which recent research reveals is important in determining their potential threat to heart conditions.
Previous studies evaluating the associations between sex hormones and cardiovascular disease as women went through menopause looked only at cholesterol measured through conventional blood tests that missed important parameters like size. The Pitt Public Health team found that as estrogen levels fall, women have higher concentrations of low-quality, smaller, denser LDL and HDL particles, which are associated with greater risk of heart disease.
With the new method, the researchers measured the size, distribution, and concentration of lipoproteins that carry cholesterol in the blood. The study subjects were 120 women, with an average age of 50 years, six months, and not on hormone replacement therapy. They were enrolled in the Study of Women's Health Across the Nation (SWAN).
"As a woman transitions to menopause, many biological changes take place that can put her at greater risk of many conditions, including osteoporosis and heart disease," said Dr. El Khoudary. "Our most recent study underscores the importance of having clinicians aware of these risk factors and prepared to work with their patient to help her best mitigate these risks."
These results should be taken as a starting point to conduct more studies on the type of treatment that women undergoing menopause should receive to lower their risks of cardiovascular diseases, say the researchers.
Source: El Khoudary S, Brooks M, Thurston R, Matthews A. Lipoprotein subclasses and endogenous sex hormones in women at midlife. The Journal of Lipid Research. 2014.