ANN ARBOR—The loss of bone density after menopause has long been linked to the dramatic decrease in the estrogen hormone, estradiol.

But a series of studies that has carefully tracked hormone levels and bone density in women aged 40 to 55 over the course of a decade has found that estrogen may not be the only hormone that should be considered.

“For years, the model has been that ovaries lose their ability to make a potent estrogen at menopause, and that this estrogen decline starts the bone loss,”