Replacement estrogen therapy for premenopausal women with secondary hypogonadism (exercise/weight loss amenorrheas) remains controversial. In a group of 14 women with anorexia nervosa, amenorrhea, and no evidence of other endocrinopathy or protein-calorie malnutrition, significant osteopenia was demonstrated as assessed by cortical thickness of carpal bones. The degree of bone thinning was related to the duration and age at onset of amenorrhea as well as abnormalities of pubertal milestone progression. In young women with 'constitutionally delayed' menarche, or with secondary amenorrhea and hypogonadism, significant osteopenia may also be present. For those women with (1) hypoestrogenism and amenorrhea of over 36 months' duration, (2) pubertal delay, and (3) early onset of secondary amenorrhea, evaluation of osteopenia radiographically, and serious consideration for estrogen replacement, is important.
Ayers, J. W. T., Gidwani, G. P., Schmidt, I. M. V., & Gross, M. (1984). Osteopenia in hypoestrogenic young women with anorexia nervosa. Fertility and Sterility, 41(2), 224–228. https://doi.org/10.1016/S0015-0282(16)47594-1