Vitamin D is an important factor for bone mineralization, prevention of osteomalacia, muscle strength and balance. The reported ideal level of vitamin D is 30 ng/mL or greater as measured by serum 25-hydroxyvitamin D (25 (OH)D). A primary source of Vitamin D is conversion in the skin through sun exposure; therefore, vitamin D inadequacy may be perceived as less of an issue in southern latitudes. However, few data have described the vitamin D distribution in the sunnier latitudes among those who are osteoporotic. We report the prevalence of vitamin D inadequacy in an osteoporosis population living in Southern California. Study sample were consecutive community-dwelling women referred to an osteoporosis clinic in Southern California from November 2003 to April 2004 following fragility fracture (37%) or with a bone mineral density T-score less than -2.5 (63%). Vitamin D levels were assessed by measuring serum 25 (OH)D levels at a central laboratory (Quest Diagnostic Lab: Diasorin radioimmunoassay [RIA]). A blood specimen was collected at the time of assessment, prior to any treatment for osteoporosis. Demographics were obtained by patient self-report. Results of 25(OH)D levels were available for 252 women and are included in the current analysis. Patients were Caucasian (78%), Asian (8%), Hispanic (4%) and African American (2%) with mean age 71 (range 45 - 91). The mean 25 (OH)D level was 29 ng/mL (SD 13) with a range of 5-70 ng/mL. 53% of the patients had 25 OHD levels <30 ng/mL: 42% ≤ 25 ng/mL, 29% ≤ 20 ng/mL, 13% ≤ 15 ng/mL, and 4% ≤ 9 ng/mL. Mean 25 OHD levels were not significantly different between women under 65 years (mean 29.0, SD 12.7) and women 65 years and older (mean 29.4, SD 13.1) or between Caucasian (mean 29.9, SD 13.4) and non-Caucasian (mean 27.3, SD 11.5) women. About one-half of the osteoporotic women in this study located in southern California had vitamin D inadequacy. Vitamin D inadequacy is common in community dwelling women, even those who live in southern latitudes. Significant opportunity exists to ensure adequate and persistent vitamin D intake in patients at risk for fractures and osteoporosis.
Disclosure Information:
Faculty Member's Name: Ya-Ting Chen, PhD
Other Financial or Material Support: Employee of Merck & Co., Inc.
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