Hormone replacement therapy (Hrt) And bone mineral density in anorexia nervosa: A 3-YEAR prospective observational study

Abstract

BACKGROUND: Osteopenia is a serious complication of anorexia nervosa. Although in other states of estrogen deficiency, estrogen replacement therapy increases bone mass, its role in anorexia nervosa remains unresolved.OBJECTIVE: To study the effect of estrogen-progestin administration on bone mass in anorexia nervosa.DESIGN: A longitudinal prospective observational study.METHODS: Bone mineral density (BMD) of the lumbar spine and left hip were prospectively measured using dual energy X-ray absorptiometry at baseline and annually in 50 adolescents with anorexia nervosa (mean age 16.3 ± 1.9 years). All subjects received calcium supplementation and the same medical, psychological and nutritional intervention (Standard Rx). 22 subjects received HRT and 28 received standard Rx alone. HRT was administered daily as an oral contraceptive pill containing 20-35 mcg ethinyl estradiol. Mean length of follow-up was 22.7 ± 11.7 months.RESULTS: At presentation, patients were malnourished (79.5 ± 7.6% IBW), hypoestrogenemic (estradiol 31.2 ± 13.8 pg/mL) and osteopenic (lumbar spine BMD −2.01 ± 0.69 SD below mean for age). 92% of subjects were osteopenic and 26% met WHO criteria for osteoporosis. Body weight and not treatment group, was the major determinant of BMD. At one-year follow-up, there were no significant differences in absolute values or in net change of lumbar spine or femoral neck BMD between those who received HRT and those who received standard Rx (80% power of finding a 3% difference in BMD at 1 year). In those followed for 2-3 years, osteopenia was persistent and in some cases, progressive.CONCLUSION: In our study population, HRT did not significantly increase BMD compared with standard Rx. These results question the common practice of prescribing HRT to protect bone mass in anorexia nervosa.