Regional Osteopenia In Women With Anorexia Nervosa
Nutrition Research Newsletter, Jan, 2001
Anorexia nervosa is highly prevalent among US women and is associated with substantial bone loss. Bone loss in women with the disorder is multi-factorial. It is related in pan to estrogen deficiency and to direct effects of undernutrition. A study recently published in Annals of Internal Medicine measured bone mineral density (BMD) at several skeletal sites to determine the prevalence rates and predictive factors of regional osteopenia and osteoporosis in a large community-based sample of women with anorexia nervosa.
Women (n=130, 98% white) with anorexia nervosa underwent a 3-hour outpatient visit at the General Clinical Research Center of the Massachusetts General Hospital in Boston. Height, weight, age at menarche, time since last menstrual period, previous estrogen use, fracture history, frame size, and dietary intake were determined. BMD was determined using x-ray absorptiometry. At each skeletal site measured, patients were categorized as having normal BMD, osteopenia, or osteoporosis, according to World Health Organization criteria.
Osteopenia and osteoporosis, respectively, were seen at the anterior-posterior spine in 50% and 13% of patients, at the lateral spine in 57% and 24% of patients, and at the total hip in 47% and 16% of patients. No differences in BMD were observed between patients with anorexia nervosa alone and patients with anorexia nervosa and concomitant bulemia nervosa. Twenty-three percent of the patients were currently estrogen users and 58% were previous estrogen users. BMD did not differ at any site according to current or previous estrogen use.
Patients with primary amenorrhea (n=7) weighed less and had lower BMD at all sites than patients with secondary amenorrhea (n=123). Total calcium intake was not correlated with BMD at any site. Fifty-seven percent of patients were receiving calcium supplements, 53% were receiving a multivitamin containing 400 IU of vitamin D, and 43% were receiving both. BMD did not differ in patients receiving nutritional supplements. Weight was a significant independent predictor of BMD at all skeletal sites. Age at menarche was a significant independent predictor of BMD measured by anterior-posterior spinal densitometry. Time since last menstrual period was a significant predictor of BMD in the anterior-posterior and lateral spine.
These findings demonstrate the high prevalence and profound degree of site-specific bone loss in women with anorexia nervosa. The data suggests that patients with anorexia are at a markedly increased risk for fracture at many skeletal sites. A relatively high percentage of patients reported a previous history of fracture. BMD was reduced by at least 1.0 SD at one or more skeletal sites in 97% of women with fractures, but fracture sites were not correlated with the location of osteopenia. Lateral BMD was reduced to a greater extent that BMD at the anterior-posterior spine. More than 90% of the patients in this highly representative sample of young anorectic women demonstrated significant bone loss at one or more skeletal sites. Current weight is the best and most consistent predictor of BMD at several skeletal sites. Screening for bone loss and counseling women with anorexia nervosa about the adverse effects of low weight on the skeleton is of utmost importance.
S. Grinspoon, E. Thomas, S. Pitts, E. Gross et al. Prevalence and Predictive Factors for Regional Osteopenia in Women with Anorexia Nervosa. Ann Intern Med 133(10): 790-794 (Nov 2000) [Correspondence: Dr. Grinspoon, Neuroendocrine Unit, Bulfinch 457b, Massachusetts General Hospital, Boston, MA 02114].
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