High prevalence of hypovitaminosis D among free-living postmenopausal women referred to an osteoporosis outpatient clinic in Northern Italy for initial screening

To establish the prevalence of hypovitaminosis D among free-living postmeno pausal women referred to an osteoporosis outpatient clinic in Northern Ital y, we evaluated 25-hydroxyvitamin D (25(OH)D) levels in 570 postmenopausal women who had been consecutively referred to our clinic in the 12 months be ginning October 1995. Parathyroid hormone (PTH), serum calcium (Ca), creati nine (Cr) and osteocalcin (OC), urinary calcium (Ca24h) and creatinine (Cr2 4h), and the bone mineral density of the lumbar spine (LBMD) and femur (FBM D) were also measured. 1,25-Dihydroxyvitamin D (1,25(OH)(2)D) concentration s were measured in 23 women. All women had normal electrolyte serum concent rations and kidney function. Mean +/- SD 35(OH)D concentration was 18.3 +/- 8.3 ng/ml. A significant (p<0.001) seasonal variation was seen for both 25 (OH)D and PTH. Women were divided into two groups based on their vitamin D status: low vitamin D status (25(OH)D <12 ng/ml, n = 161, 28%) and normal v itamin D status (25(OH)D greater than or equal to 12 ng/ml, n = 409, 72%). Hypovitaminosis D was found in 38.5% of all the women in the time period De cember-May and in 12.5% in the other half-year; among women >70 years old 5 1% had hypovitaminosis D in the time period December-May and 17% in the oth er half-year. PTH was significantly (p<0.05) increased, and Ca24h, OC and F BMD significantly (p<0.05) decreased in women with hypovitaminosis D. 1,35( OH)(2)D positively correlated with 25(OH)D (p<0.0001), but did not correlat e with PTH, age or creatinine clearance. In conclusion, hypovitaminosis D i s an important, underestimated problem in Italian free-living postmenopausa l women referred to an outpatient osteoporosis clinic.