PURPOSE: Low levels of vitamin D have been found to be associated with increased susceptibility to fractures, bone pain, muscle weakness, osteomalacia and, more recently, with increased risk of falling. Serum values between 10-20 ng/ml represent vitamin D insufficiency. The optimal serum level should be above 20ng/ml, if not higher, to avoid these clinical consequences. Vitamin D insufficiency is often suspected in high-risk patients such as those who receive little or no direct sunlight, adhere to vitamin D deficient diets, have fat malabsorption syndromes, or take medications that interfere with vitamin D metabolism. Recent studies have revealed the prevalence of vitamin D insufficiency in other cohorts. Here, we reported the characteristics associated with levels of vitamin D in postmenopausal women. METHODS: We performed an observational study of postmenopausal women, aged 40-65 years, with lumbar and hip bone mineral density (BMD) T-scores between 0 and -2.5 enrolled in an osteoporosis prevention trial (NOVEL) - Nitroglycerin as an Option: Value in Early Bone Loss. Of the fourteen hundred women contacted for phone screening, 203 were eligible for screening. The subjects were characterized by demographic information, medical conditions, menopausal status, lumbar and hip T-score, vitamin D supplement use, Body Mass Index (BMI), smoking status and degree of physical activity. The primary outcome for this analysis was the serum level of vitamin D. The data was analyzed by student's T test or ANOVA as applicable. RESULTS: Of the 203 subjects, 19(9.4%) were African American. The mean age (±SD) was 59 (±4) and age of last menses 47(±5). Twenty-six (±3) was the mean BMI. The mean vitamin D level was 40 ng/ml (±17), and 8 percent had less than 20 ng/ml. As expected, the range of vitamin D level had seasonal variability. Lower vitamin D values were associated with African Americans, smokers, non-supplement use of vitamin D and subjects with exercise duration of less than one hour per week (p<0.05). Furthermore, there was no relationship of vitamin D levels observed in the BMD's T scores, or, BMI.There was a trend to lose the beneficial effect of vitamin D supplement in smokers. CONCLUSIONS: In our sample of postmenopausal women enrolled in an osteoporosis prevention trial, Eight percent had vitamin D insufficiency. Although a small cohort, our results emphasize the role that race, smoking status, vitamin D supplementation and exercise play in low vitamin D levels. These factors need to be addressed in screening for osteoporosis. Although adequate daily vitamin D intake levels of 400 IU for those aged 51-69 and 600 IU over the age 70 are recommended, greater amounts of vitamin D may be necessary. Additional studies will aid in clarifying the specific requirements for vitamin D supplementation.
Disclosure Information:
Faculty Member's Name: Julia P. Grimes, DO, MPH
Grants/Research Support: NIAMS-069 AR48679-
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