1.   Calcium absorption -- crucial to building and maintaining bone mass -- is linked to estrogen, and slows after menopause when the levels of naturally occurring estrogen drop.

2.   Premarin is made of a complex blend of naturally occurring estrogens derived from the urine of pregnant mares.

3.   The condition, in which the bones become very fragile, generally occurs after menopause when the levels of naturally occurring estrogen drop.

4.   The condition, marked by growing fragility of bones, usually occurs after menopause when the levels of naturally occurring estrogen drop.