Low 25-Hydroxyvitamin D Levels and Low Bone Density Assessed by Quantitative Ultrasonometry in a Cohort of Postmenopausal Italian Nuns

This study was aimed at evaluating the effect of clothing style on bone mass and fractures in 70 postmenopausal nuns residing in a monastery in Naples. Sixty healthy women matched for age, body mass index, and menopausal status were enrolled as controls. Each participant underwent measurement by quantitative ultrasonometry (QUS) using a DBM Sonic Bone Profiler (IGEA S.p.A., Carpi, Modena, Italy) at proximal phalanges, responded to questionnaires regarding lifestyle, calcium intake, medical history, including clinical fragility fractures, and was submitted to routine biochemical assessment. A significant reduction in ultrasonometric parameters of bone mass was found in nuns compared with controls (p from 0.007 to <0.0001). 25-hydroxyvitamin D (25-OH vit D) levels were reduced by more than 50% in nuns (9.8 ± 4.2 vs 23.5 ± 5.7 nmol/L; p < 0.0001), whereas their estimated daily calcium intake was higher (1.004 ± 0.23 vs 0.721 ± 0.25 g of controls; p = 0.0007). Age at menopause was significantly lower in nuns' group (p = 0.016). Incidence of fractures was higher in nuns (39% vs 10%; p = 0.0029), and the best predictors of fractures were age at menopause (odds ratio [OR]: 1.12; 95% confidence interval [CI]: 1.01-1.30), amplitude-dependent speed of sound T-score (OR: 1.15; 95% CI: 1.03-1.63), and bone transmission time T-score (OR: 1.30; 95% CI: 1.15-1.81). This study documented low 25-OH vit D levels, increased frequency of clinical fractures, and low bone mass detected by QUS in Southern Italian nuns.