Osteoporosis estrogen therapy

Age, calcium intake, hormonal status, exercise and vitamin status have all been implicated in the development of osteoporosis. Estrogen levels represent an important factor in skeletal calcium retention and homeostasis. In therapeutic trials in which post-menopausal women were given daily doses of estrogens, such therapy has been demonstrated to be partially effective in reducing the rate of bone resorption. However, this therapy has the concomitant hazard of endometrial cancer (10). Vitamin D and its hormones have been given considerable attention in the more recent studies. Without adequate dietary and tissue levels of such vitamins, calcium absorption and bone status will be impaired. 

Estrogen replacement therapy was until recently widely recommended for the prevention of osteoporosis in middle-aged and older women (1). Long-term estrogen therapy also reduces the incidence of ischemic heart disease in such women (2). However, it has always been difficult to know in which women such prophylactic use is likely to be needed, and this dilemma is compounded by the prospect of adverse reactions, which can include any of the acute effects listed in the estrogen monograph, but also in some cases long-term effects such as tumors. 

C. Pulsed estrogen therapy in prevention of postmenopausal osteoporosis a 2-year randomized, double blind, placebo-controlled study. Osteoporos Int 2004 15 168-74. 

The most frequent uses of estrogens are for contraception (see p. 268), for postmenopausal hormone therapy and for osteoporosis. Estrogens are also used extensively for replacement therapy in patients deficient in this hormone. Such a deficiency can be due to lack of development of the ovaries, menopause, or castration. 

Calcitonin therapy results in decreased bone resorption. Osteoclasts have calcitonin receptors and calcitonin inhibits their activity. Sodium fluoride stimulates bone formation by unknown mechanisms. In women with osteoporosis, fluoride therapy produced an increased bone mineral density but no reduction in the rate of vertebral fractures. Other drugs known as selective estrogen receptor modulators (raloxifene, droloxifene, idoxifene, and levormeloxifene) may provide an alternative to estrogen replacement therapy (Chapter 34). Administration of low doses of PTH [or recombinant PTH( 1 -34)] does not affect serum calcium concentration, promotes bone formation, and increases mineral density. This anabolic action of PTH is probably mediated by decreasing osteoblast apoptosis. 

Genant HK, Lucas J, Weiss S, et al. Low-dose esterified estrogen therapy Effects on bone, plasma estradiol concentrations, endometrium, and lipid concentrations. Estratab/Osteoporosis Study Group. Arch Intern Med 1997 157 2609-2615. 

Genant, H. K., Lucas, J., Weiss, S., Akin, M., Emkey, R., McNaney-Flint, H., Downs, R., Mortola, J., Watts, N., and Yang, H. M. (1997). Low-dose esterified estrogen therapy Effects on bone, plasma estradiol concentrations, endometrium, and lipid levels. Estra-tab/Osteoporosis Study Group. Arch. Intern. Med. 157, 2609-2615. 

Lindsay, R. (1987). Estrogen therapy in the prevention and management of osteoporosis. Am. J. Obstet. Gynecol. 156,1347-1351. 

Estrogen therapy with dienestrol has been shown to increase the number and thickness of bone trabeculae, previously atrophic, with an increase in the number of osteoblasts and abnormally wide osteoid seams in osteoporosis complicating Paget s disease. The effect of dienestrol has also been studied in postmenopausal osteoporosis and the beneficial effect appears to be maximal only when the intakes of calcium and phosphorus are both about twice the accepted optimal requirements. ... 

Heterocycles as synthetic estrogens in emerging therapies for the prevention or treatment of postmenopausal osteoporosis 99JMC1. 

Estrogens and progestins are diminished in menopausal or ovarectomized women. In hormone replacement therapy (HRT), these hormones are substituted to alleviate hot flushes, mood changes, sleep disorders, and osteoporosis. 

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