Endocrine Abstracts

JOINT2532

Background: Low bone mineral density (BMD) is a common feature of Turner syndrome (TS), frequently with an early onset, whose pathogenetic mechanisms and risk factors are not completely elucidated.

Aim: To evaluate the prevalence of low BMD, clinical fractures, and associated risk factors in a large population of adult TS patients attending a tertiary hospital with a structured transition program.

Methods: A cross-sectional analysis was conducted on 176 patients with TS (median age:36. 1yrs, range:15. 3-70. 7) at the time of their most recent dual-energy X-ray absorptiometry (DXA). Anthropometrics, bone metabolism markers, karyotype, typical comorbidities, details about prior and current estrogen replacement treatment (ERT) and prior rhGH treatment (rhGHT) were evaluated to assess their impact on lumbar/hip BMD, Z-scores and fracture risk.

Results: Seventy-one patients (40. 3%) presented a 45, X0 karyotype. Spontaneous menarche occurred in 36 patients, and 19 subsequently developed secondary amenorrhea. ERT was started at a median age of 16. 0yrs (range: 8. 0-50. 0), lasting 19. 0yrs (range: 0. 0-45. 0). rhGHT was administered in 120 patients (69. 8%). Regarding bone metabolism, 46 patients (27. 7%) exhibited low BMD (lumbar/hip Z-score≤-2), 13 (7. 4%) experienced clinical fractures. Ten patients (5. 7%) were on antifracturative treatment. Patients with low BMD had later induced/spontaneous menarche (17. 0 vs 16. 0yrs, P = 0. 047), higher prevalence of primary amenorrhea (93. 5% vs 75. 4%, P = 0. 009) and of family history of osteoporosis/fractures (27. 3% vs 8. 2%, P = 0. 025) compared with patients with normal BMD. No significant differences were found in biochemical calcium-phosphate markers, bone turnover markers, and both sub-groups had adequately supplemented vitamin D levels. Age, karyotype, prior rhGHT, and prior or current ERT analysed as daily dose, type of estrogen, route of administration and duration, were not different between the two sub-groups. Patients with fragility clinical fractures had lower lumbar Z-scores (-2. 0 vs -1. 1, P = 0. 042), and higher prevalence of other typical TS comorbidities (diabetes mellitus, major/minor cardiovascular events, hypertension, nephropathy), despite no age or BMI differences. No significant differences were also noted in karyotype, ERT or rhGHT. Notably, five patients with normal BMD experienced fragility fractures. However, DXA remained a reliable predictor of fractures, as patients with low BMD exhibited a significantly higher fracture risk (OR=4. 84, 95CI:1. 49-125. 70, P = 0. 009).

Conclusions: TS are at high risk for low BMD and fragility fractures, regardless of karyotype, rhGHT and type and extension of ERT. At variance, a delayed ERT initiation, as well as primary amenorrhea, are risk factors for low BMD. Therefore, continuous, lifelong monitoring of bone health is essential for all TS patients.