HRT may promote reverse cholesterol transport through induction of cholesterol ABC transporters. HRT also results in a large reduction in the pro-thrombotic lipoprotein a. Studies on cardiovascular disease with testosterone therapy have been mixed, with some suggesting no effect or a mild negative effect, though others have shown an improvement in surrogate markers such as cholesterol, triglycerides and weight. Testosterone has a positive effect on vascular endothelial function and tone with observational studies suggesting that women with lower testosterone may be at greater risk for heart disease. Available studies are limited by small sample size and study design. Low sex hormone binding globulin, which occurs with menopause, is associate with increased body mass index and risk for type 2 diabetes. Blood clots
Effects of hormone replacement therapy on venous blood clot formation and potential for pulmonary embolism may vary with different estrogen and progestogen therapies, and with different doses or method of use. Comparisons between routes of administration suggest that when estrogens are applied to the skin or vagina, there is a lower risk of blood clots, whereas when used orally, the risk of blood clots and pulmonary embolism is increased.
Most classifications of bioidentical hormones do not take into account manufacturing, source, or delivery method of the products, and so describe both non-FDA approved compounded products and FDA approved pharmaceuticals as bioidentical. The British Menopause Society has issued a consensus statement endorsing the distinction between "compounded" forms (cBHRT), described as unregulated, custom made by specialty pharmacies and subject to heavy marketing and "regulated" pharmaceutical grade forms (rBHRT), which undergo formal oversight by entities such as the FDA and form the basis of most clinical trials. Some practitioners recommending compounded bioidentical HRT also use salivary or serum hormonal testing to monitor response to therapy, a practice not endorsed by current clinical guidelines in the United States and Europe.Bioidentical hormones in pharmaceuticals may have very limited clinical data, with no randomized controlled prospective trials to date comparing them to their animal derived counterparts. Some pre-clinical data has suggested a decreased risk of venous thromboembolism, cardiovascular disease, and breast cancer. As of 2012, guidelines from the North American Menopause Society, the Endocrine Society, the International Menopause Society, and the European Menopause and Andropause Society endorsed the reduced risk of bioidentical pharmaceuticals for those with increased clotting risk. Compounding
Compounding for HRT is generally discouraged by the FDA and medical industry in the United States due to a lack of regulation and standardized dosing.