Risk factors for vitamin D deficiency in women aged 20-50 years consulting in general practice: a cross-sectional study

Objective: Vitamin D deficiency is often unidentified, although treatment is simple and inexpensive. Our objective was to estimate the influence of concealing clothes and other risk factors for vitamin D deficiency in women aged 20 to 50 years consulting general practitioners. Methods: 13 GPs in the Rhone Alps area planned to recruit 300 women (100 veiled and 200 non-veiled) from January to March 2008. Serum 25(OH)D and PTH were measured in one single laboratory (Biomnis(R)) by a radio-immunoassay method. A survey was administered about dietary habits, sun exposure, and quality of life. Results: Among 247 women enrolled, 196 were analysed: 61 wearing concealing clothes (31.2%) and 135 without (68.8%). As expected, 25(OH) D serum level was significantly lower in covered women (20.1 versus 38.9 nmol/l P < 0.001). Of women who did not wear concealing clothing, 39.3% had severe hypovitaminosis D (25(OH) D concentration < 30 nmol/l). Women wearing concealing clothes had more often other known risk factors such as dark skin (P < 0.001), less sunlight exposure, or a higher Body Mass Index (P = 0.009). Besides concealing clothing (OR 6.37, 95% CI: 1.35-30.09), multi-variate analyses revealed two independent risk factors for vitamin D deficiency: no full-body sun exposure (OR: 3.06, 95% CI: 1.18-7.94) and no outdoor sports (OR: 2.81, 95% CI: 1.11-7.12) for threshold 52 nmol/l. Conclusion: Young women consulting their GP had hypovitaminosis D more often than expected. Besides concealing clothing, absence of full body sun exposure during summer and of outdoor sports practice could suggest a possible vitamin D deficiency.