Table 1.

Management of low bone density in AN

	Adolescent girls	Postmenopausal women
Lifestyle advise	Decrease exercise and increase weight gain  Calcium and vitamin D	Decrease exercise and increase weight gain Calcium and vitamin D
When to initiate pharmacological therapy?
FRAX	(FRAX is not intended for use in persons < 40 years)	No specific guidelines for adults with AN
DXA	Z-score ≤ −2+ decreasing over time despite all efforts at weight gain [5, 9]	No specific guidelines for adults with AN
Which pharmacological therapy?
Recommended	Lower-dose physiologic estrogen [10] MHT (100 µg transdermal 17-beta-estradiol with cyclic micronized progesterone)	In adults with osteoporosis  MHT (100 µg transdermal 17-beta-estradiol with cyclic micronized progesterone) in women aged 50–60 years*  Bisphosphonates*  Denosumab* (schemes & doses for postmenopausal osteoporosis)
Not recommended	High-dose estrogen (oral contraception) [11] (“pill” containing 50 µg ethynilestradiol)  Androgen replacement [5]  Recombinant human insulin-like growth factor 1 (rhIGF-1) (under investigation) [5]  Bisphosphonates  Denosumab  Teriparatide	In adults with AN-associated bone loss  Additional research is needed to confirm efficacy and safety of bisphosphonates [12]  No data regarding use of Denosumab [5]  Role for Teriparatide not yet clear (under investigation) [5, 12]

*Few series