Estrogen Treatments for Osteoporosis

Estrogen Replacement After Menopause

Overwhelming evidence has established a major role for estrogen replacement following menopause as a means to conserve bone mass.  Moreover, estrogen replacement protects against osteoporotic bone fractures.  Both oral estrogen as well as trans-dermal (the patch) reduce bone turnover and therefore conserve bone mass.  Protection against hip fractures probably requires 5 years of estrogen therapy, and stopping the medication will likely lead to acceleration of bone loss and a return of the osteoporosis risk of fracture.  Therefore, once initiated, a woman should probably stay on estrogens to continue to receive their benefits.

Standard practice requires the administration of progesterone hormones along with the estrogens to women who have an intact uterus.  This progesterone can be given in several forms, and it can be administered continuously, or periodically during the month.   The most common form of progesterone prescribed (medroxyprogesterone acetate) will not interfere (nor augment) the beneficial skeletal effects of estrogen.  In Europe, some other types of progesterones which have some androgenic hormone effects may actually have an added benefit of increasing bone mass (not just preserving it like plain estrogen)   For women without a uterus, estrogen replacement is continuous and there is no need for progesterone hormones.

When to Start Estrogen Replacement

The ideal time to begin estrogen replacement is when bone turnover (remodeling) becomes more frequent thereby accelerating osteoporosis.  This typically occurs during early menopause.  Most endocrinologists believe, however, that bone preserving benefits of estrogens can still be achieved even when it is started more than a decade after menopause.  Evidence for this is found in the large clinical trials which included many women in their 60's in the group that had decreased osteoporosis and bone fractures when taking estrogens.  There is not much scientific information regarding the potential benefits of starting estrogen replacement therapy (for the first time) in women over 70.

Designer Estrogens and SERMs (Evista)

Raloxifene  (Evista) is a member of a new group of drugs loosely referred to as "designer estrogens". This group of drugs is referred to as SERMS for "Selective Estrogen Receptor Modulators".  Raloxifene behaves like the natural occurring estrogen (17-beta estradiol) in the liver where it increases production of HDL cholesterol (the "good" cholesterol), and reduces LDL cholesterol (the "bad" cholesterol).  It also appears to have all the beneficial effects of the naturally occurring estrogen on maintenance of bone density, and also helps the kidneys produce vitamin D.  However, this drug appears to have NO effect on the growth of the endometrial lining of the uterus so there is no need for progesterone hormones and there is no periodic bleeding or spotting.   Furthermore, Raloxifene may be an anti-estrogen for the breast (Tamoxifen is a different class of anti-estrogens which has no effect on bone mass, but has recently been shown to decrease the risk of breast cancer in women who took it for several years).   Raloxifene has been FDA approved for the prevention of menopausal bone loss for several years, and in clinical trials in patients with established osteoporosis has been shown to build bone in most women and some groups of men.