6396 Bone densitometry findings and prevalence of osteoporosis at initial scanning in children and young people with anorexia nervosa

Objectives NICE recommends dual energy x-ray absorptiometry (DXA) scan after 1 year of underweight in children and young people (CYP) with Anorexia Nervosa (AN).¹ Optimal timing and specific indications for DXA remain unknown. We aimed to: 1) evaluate DXA findings in girls with AN at referral and compare groups based on menstrual status. 2) determine the prevalence of osteoporosis [defined as the presence of vertebral fractures (VF) or both a clinically significant fracture history (long bone fractures: ≥2 by 10 years or ≥3 at any age up to age 19 years) and low bone mineral density (BMD) Z-score ≤-2.0]. Methods Retrospective review of patients with AN referred for initial DXA scan at a tertiary paediatric regional unit between March 2013 and October 2022. A questionnaire was used to gather self-reported fracture history and pubertal status. Pubertal status was classified as normal, delayed (no breast development by 13 or no menarche by 15years), irregular menstruation (amenorrhoea< 3 months or a missed period) or secondary amenorrhoea (no menstruation >3 months with previously regular menses) or unknown (insufficient data). Data on anthropometry, lumbar spine (L1-L4) bone mineral apparent density (BMAD), total body less head (TBLH) BMD Z-scores and VF were gathered. Results A total of 264 CYP with a median (range) age of 15.6 (10.2–19.8) years were included. The majority, 54.5%, reported secondary amenorrhoea (n=144) and 14.8% (n=39), 14% (n=37), 13.6% (n=36) and 3% (n=8) reported normal, delayed, irregular menstruation and unknown pubertal status respectively. The mean (SD) weight SDS [-1.1 (1.3)] and BMI SDS [-1.2 (1.2)] were significantly lower than zero (p<0.001). LS BMAD and TBLH BMD Z-scores were significantly different between the pubertal groups (p<0.05) and low bone density (low LS BMAD Z-score and/or TBLH BMD Z-score) was evident in 18.9% (n=50/264). LS BMAD and TBLH BMD Z-scores (SD) in CYP with normal, delayed puberty, irregular menses and secondary amenorrhoea were -0.8(0.2), -1.3(0.2), -1.1(0.2), -0.8(0.1) respectively and -1(0.1), -1.1(0.1), -0.8(0.1), -0.7(0.1) respectively. Long bone fractures were reported by 16.7% [n=44/264, 3% (n=8, all >10 years) reporting x2 fractures]. VF were noted in 1% (n=3) who met the criteria for osteoporosis. Conclusion Low bone density is frequent in CYP with AN, however osteoporosis is rare which calls for a review of the referral criteria for DXA scanning. CYP with delayed puberty are at highest risk of low bone density possibly due to lack of primary exposure to oestrogen. Reference Eating disorders: recognition and treatment, National Institute for Health and Care Excellence (NICE) guideline [NG69], Published 23 May 2017 and updated on 16 December 2020. Available from: https://www.nice.org.uk/guidance/ng69/ifp/chapter/Anorexia-nervosa-treatment-for-children-and-young-people