Effects of hormone replacement therapy

According to the World Health Organization, the global life expectancy at birth was 55 years in 1974, will be 63 years in 2000, and will be close to 70 years in the year 2025. By the year 2025, approximately 20% of the world's population will be more than 60 years old, and the problems associated with hormonal changes become significant with more than one third of a woman's expected life concentrated in the postmenopausal years. Much evidence suggests that the use of postmenopausal estrogen substantially reduces the morbidity and mortality of coronary heart disease, and to date, low-dose estrogen therapy is the single most effective method for prevention of osteoporosis. However, only hysterectomized women can use estrogen alone because of the risk of endometrial cancer associated with unopposed estrogen therapy. Thus, women with an intact uterus must use estrogen in combination with progestogen to avoid this risk, but the different progestogens may variously modify the beneficial effects of estrogen on lipoproteins, and, ultimately, coronary heart disease. Although hormone replacement therapy during menopause soon will be one of the major areas of preventive medicine, the effects of estrogen in combination with different progestins on coronary heart disease, blood pressure, blood coagulation, bone density, and the central nervous system have not been investigated adequately. This paper reviews the current knowledge of known or suspected effects.