Vitamin D inadequacy in French osteoporotic and osteopenic women

Studies have shown that low serum vitamin D levels are associated with secondary hyperparathyroidism, which decreases bone strength and increases fracture risk, most notably after 50 years of age. The objective of this study was to evaluate the vitamin D status of postmenopausal women in France.

We conducted a cross-sectional observational study of 1292 menopausal women with osteoporosis or osteopenia. The age range was 52-94 years. Serum 25-OH-vitamin D was assayed in each patient. Based on data in the literature, we used four 25-OH-D cutoffs to define vitamin D deficiency: 30, 50, 75, and 80 nmol/L (<12, <20, <30, and <32 ng/ml).

Mean serum 25-OH-D was 51.5+/-26.1 nmol/L (about 20.6+/-10.4 ng/ml). In the 343 (26.5%) patients taking supplemental vitamin D with or without supplemental calcium, the mean serum 25-OH-D level was significantly higher than in the other patients (65.0+/-26.0 ng/ml vs. 46.6+/-18.6 ng/ml; P<0.001). In the subgroup not taking vitamin D supplements, the prevalence of vitamin D deficiency was 27.3%, 54.1%, 89.9%, and 93.2% with the 30, 50, 75, and 80 nmol/L cutoffs, respectively. The mean 25-OH-D level varied across seasons (P<0.001), with the highest value being obtained in summer (53.4+/-18.7 nmol/L; about 21.3+/-7.5 ng/ml).

Vitamin D deficiency is common among postmenopausal women with osteoporosis or osteopenia in France.