Estrogen replacement improved BMD in girls with anorexia nervosa

Issue: July 2011

ENDO 2011

BOSTON — Girls with anorexia nervosa who were given estrogen therapy in the form of a patch or a low oral dose experienced improvements in bone mineral density, researchers reported here.

"Low bone density and decreased rates of bone accrual areis a common effect of anorexia nervosa that results from several factors, including low levels of estrogen, which typically helps prevent bone loss," Madhusmita Misra, MD, a pediatric endocrinologist at Massachusetts General Hospital for Children and associate professor of pediatrics at Harvard Medical School, said at a press conference. "The lowLow rates of bone density accrual during adolescence may lead to suboptimal peak bone mass and an increased risk of impaired bone health and increased fracture risk in later life."

According to Misra, the low BMD is most severe at the lumbar spine in girls with anorexia nervosa. Although recovering from anorexia nervosa is related to improved BMD, there are typically some residual deficits.

“There are few therapeutic strategies that increase BMD in girls with anorexia nervosa,” Misra said. “Previous studies have shown that oral estrogen combined with progesterone as birth control pills does not improve BMD in this condition. However, giving estrogen in a more natural form has not previously been studied."

Misra and colleagues evaluated the effect of estrogen on BMD in a study that included 110 girls with anorexia nervosa and 40 normal-weight controls. All were aged 12 to 18 years, a common time when girls may develop the eating disorder. The researchers assessed the participants’ bone maturity using wrist and hand X-rays.

Girls with immature bones (aged younger than 15 years) were randomly assigned to receive low-dose oral ethinyl estradiol or placebo. They received 3.75 mcg from 0 to 6 months; 7.5 mcg from 6 to 12 months; and 11.25 mcg from 12 to 18 months. Girls with mature bones (aged 15 and older) were randomly assigned to transdermal estradiol or placebo for 18 months. These girls were also given cyclic progesterone pills. The 40 healthy controls received only calcium and vitamin D supplements, which were also given to all participants.

The researchers evaluated BMD at the lumbar spine and hip using DXA scans. Overall, BMD measures were lower in girls with anorexia nervosa compared with controls at baseline. In girls with anorexia nervosa who did not receive estrogen, changes in measures of lumbar BMD and hip BMD were significantly lower at 6, 12 and 18 months compared with girls with anorexia nervosa who did not receive estrogen and normal-weight controls. Those who received estrogen had significantly greater increases in measures of lumbar BMD and hip BMD compared with girls who did not receive estrogen, and were comparable to the controls.

“In addition to weight gain, physiological estrogen could be a potential therapeutic option for optimizing bone mass in girls with anorexia nervosa,” Misra said. “The decision to treat would depend on the individual patient and her fracture risks.” - by Emily Shafer

Disclosure: Dr. Misra reports no relevant financial disclosures.

For more information:

Misra M. #OR29-2. Presented at: The Endocrine Society 93rd Annual Meeting & Expo; June 4-7, 2011; Boston.

For a long time, it was thought that low BMD in anorexia nervosa was related to low estrogen. But, it was found that giving pharmacologic doses of estrogen to these patients did not increase their BMD. This study looked at whether giving low-dose physiologic doses of estrogen might make a difference. It is relevant, clinically, in that for many who have anorexia nervosa, low BMD is not only a problem during the active phase of the disease, as well as for people who have recovered from anorexia nervosa. Anything that identifies ways in which a clinical intervention to help increase the BMD is great. This study also suggests the potential to look at whether other causes for low BMD can also respond to low-dose physiologic estrogen.

– Tamara Wexler, MD, PhD
Attending in Medicine
Massachusetts General Hospital

Disclosure: Dr. Wexler reports no relevant financial disclosures.

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