Starting age of oestrogen‐progestin therapy is negatively associated with bone mineral density in young adults with Turner syndrome independent of age and body mass index

Objective Osteoporosis is an important health issue in patients with Turner syndrome (TS), and oestrogen sufficiency has been implicated in increased bone mineral density (BMD); however, the impact of the starting age of hormone replacement therapy (HRT) on bone mineral density remains unclear, particularly during young adulthood. Design A retrospective study from three tertiary care hospitals in Japan. Patients One hundred and three patients with TS aged between 18 and 30 years of age who underwent dual‐energy X‐ray absorptiometry. Measurements Anthropometric parameters, lumbar bone mineral density (L‐BMD), including areal BMD (aBMD) and volumetric BMD (vBMD), karyotypes, the presence of spontaneous menarche, the starting ages of oestrogen replacement therapy (ERT) and oestrogen‐progestin therapy (EPT), and the duration between starting ages of oestrogen replacement therapy and oestrogen‐progestin therapy were investigated. vBMD was calculated based on the Kröger method. Results aBMD was lower in young adults with TS than in an age‐matched reference population. L‐BMD positively correlated with weight and body mass index (BMI). L‐BMD was higher in subjects with spontaneous menarche (N = 22) than in those without. A dose escalation regimen of oestrogen replacement therapy was used in 84% of subjects without spontaneous menarche (N = 81). The starting age of oestrogen replacement therapy and the duration between the starting ages of oestrogen replacement therapy and oestrogen‐progestin therapy negatively and independently correlated with aBMD, but not with vBMD, after adjustment with age and BMI. The starting age of oestrogen‐progestin therapy negatively correlated with L‐BMD independent of age and BMI. Conclusions Early introduction of hormone replacement therapy, particularly oestrogen‐progestin therapy, is important to accrue better L‐BMD in young adults with TS.