Screening, treatment of osteoporosis in premenopausal women unclear

Recent research suggests that a higher percentage of premenopausal women than previously reported may have idiopathic osteoporosis, in turn experiencing one or more low-trauma fractures and/or having very low bone density.

In a study published in the Journal of Women’s Health, researchers at Columbia University in New York evaluated 61 premenopausal women at an osteoporosis referral center. Of these women, 39% were considered to have idiopathic osteoporosis, with no known secondary cause identifiable.

“It is important to evaluate premenopausal women for secondary causes of osteoporosis in order to guide treatment of their condition,” Adi Cohen, MD, MHS, of the division of endocrinology in the department of medicine at Columbia University College of Physicians and Surgeons, told Endocrine Today, a sister publication of Orthopedics Today. “In some women, no secondary cause can be found. More information is needed to determine appropriate clinical management for these women.”

She added: “There is an important distinction between people diagnosed on the basis of low bone density and those diagnosed based upon fracture. Those who have low trauma fractures are said to have osteoporosis, but those who have only low bone density and no known secondary cause may or may not actually have compromised bone strength.”

Fractures and low bone mass are less common in premenopausal women than postmenopausal women and are usually attributed to secondary causes such as estrogen deficiency, glucocorticoid exposure or hyperparathyroidism, according to Cohen. Low bone mass in premenopausal women may be related to inadequate peak bone mass acquisition or ongoing bone loss.

Who to screen, who not to screen

Bone density screening by DXA is not routinely recommended to define osteoporosis in premenopausal women.

“Bone density measurements do not clearly predict fracture risk in young premenopausal women the same way that they do in postmenopausal women. Data obtained from a bone density test in a younger woman are not nearly as helpful in determining the need for treatment,” Cohen said.

On the other hand, bone density measurement is recommended for premenopausal women with known secondary causes of osteoporosis or history of fragility fracture.

“There are categories of young women who should have bone density testing, and that includes women who have a secondary cause of osteoporosis, such as glucocorticoid treatment, gastrointestinal malabsorption, anorexia nervosa or other causes of amenorrhea,” Cohen said.

Medical record review

In the Journal of Women’s Health study, Cohen and colleagues reviewed medical records for all premenopausal women with low BMD and/or low-trauma fracture evaluated at the Columbia University referral center during 2005 (n=61; mean age, 37 years; 93% white). Fifty-seven percent of women had a family history of osteoporosis and 43% had been given bisphosphonates. The researchers aimed to estimate the proportion of premenopausal women with idiopathic osteoporosis as opposed to secondary osteoporosis.

The most common secondary causes of osteoporosis were amenorrhea (34%), anorexia nervosa (16%) and glucocorticoid exposure (13%). After exclusion of secondary causes, 39% of the overall cohort and 48% of women with fractures had idiopathic osteoporosis.

“A certain percentage of the group did not have any cause after extensive evaluations,” Cohen said. “We learned a lot from this chart review.”

In addition, women with known secondary causes had lower BMD z scores at the spine and hip compared with those with idiopathic osteoporosis. Women with low BMD and no fractures had shorter stature and weighed less than women with fractures.

“The smaller stature of women diagnosed only on the basis of BMD criteria raises the question of whether their areal BMD measurements are spuriously low because of smaller bone size,” the researchers wrote.

Reference:
Cohen A, Fleischer J, Freeby MJ, et al. Clinical characteristics and medication use among premenopausal women with osteoporosis and low BMD: The experience of an osteoporosis referral center. J Women’s Health. 18(1): 79-84.