Delay in estrogen commencement is associated with lower bone mineral density in Turner syndrome

Objective: Turner syndrome (TS) is associated with hypogonadism, osteoporosis and fractures. We investigated the prevalence and risk factors for low bone density and fractures in a TS cohort. Methods: We included 76 TS patients (median age 28.5 years) attending a tertiary hospital between 1998 and 2015 who underwent dual-energy X-ray absorptiometry. Spine and femoral neck (FN) areal bone mineral density (aBMD) were compared with those of a control group. To adjust for smaller bone size, bone mineral apparent density (BMAD) was calculated. Results: Primary amenorrhea was common (83%) in the TS cohort; the median age of pubertal induction was 15 years (range 11–30 years), and non-continuous estrogen therapy (ET) recorded in 40%. Almost one-third of TS patients reported fractures. TS patients had lower median spinal aBMD (1.026 g/cm² vs. 1.221 g/cm²) and BMAD (0.156 g/cm³ vs. 0.161 g/cm³) than controls, and lower median FN aBMD (0.850 g/cm² vs. 1.026 g/cm²) (all p < 0.01). More women with TS had spinal Z-score < −2.0 compared to controls (26.0% vs. 3.6%, p = 0.001). Spine and FN aBMD, BMAD and Z-scores were inversely associated with age commencing ET or years of estrogen deficiency. Conclusions: Delay in ET commencement was an independent risk factor for the lower bone density observed in women with TS. Early pubertal induction and ET compliance are important targets to optimize aBMD.