Young women who suffer from primary ovarian insufficiency (POI), which causes the body to stop producing estrogen can rely on hormone replacement therapy to return their levels back to normal. Researchers at the National Institutes of Health published their findings in the Journal of Clinical Endocrinology & Metabolism.

One in 100 women suffers from spontaneous POI by the time they’re 40 years old due to anorexia, chromosome abnormality, or chemotherapy. Women with POI have abnormally low levels of reproductive hormones, such as estradiol, testosterone, progesterone, and estrogen, which cause a decrease in bone mineral density much like osteoporosis.

“Bone mineral density is an important measure of bone health. This study showed that not only could hormone treatment reduce the rate at which women with POI lose bone mineral density, but it could actually restore bone density to normal levels,” Dr. Lawrence M. Nelson, the study’s lead author and investigator in the Program on Reproductive and Adult Endocrinology at the National Institute of Child Health and Human Development, said in a press release.

Being able to restore bone density in women will decrease their susceptibility to breaks in the bones. Researchers looked at the effects of two hormone replacement therapies on the hip and lower spine of 145 women 18 to 42 years old. The women were split into two groups: One was treated with an estradiol patch, testosterone patch, and progestin pills, while the other group received an estradiol patch, progestin pills, and a placebo patch. The scientists measured the bone density in both groups, along with an untreated group of 70 women with normal hormone levels.

“While hormone replacement therapy’s effect on bone mineral density has been studied in postmenopausal women, there is limited research on the effects of this therapy in younger women,” said lead author Dr. Vaishali B. Popat, an endocrinologist who helped conduct the study at NIH.

Both groups of women with POI benefited from the treatment, regardless of the addition of the testosterone patch, and by the end of the study, all of the treated women had such a significant increase in their bone mineral density that it reached the same levels of healthy women without POI.

“This study provides important evidence that hormone replacement therapy with an appropriate dose of estradiol delivered via a skin patch combined with oral progestin can improve bone density to normal in women with primary ovarian insufficiency,” Popat said.

Source: Popat VB, Calis KA, Kalantaridou SN, et al. Bone Mineral Density in Young Women With Primary Ovarian Insufficiency: Results of a Three-Year Randomized Controlled Trial of Physiological Transdermal Estradiol and Testosterone Replacement. The Journal of Clinical Endocrinology & Metabolism. 2014.