Survey of vitamin D levels among post-menopausal Filipino women with osteoporosis

Objective: To determine the prevalence of vitamin D inadequacy in a group of Filipino post-menopausal women with osteoporosis. Methods: Seventy otherwise healthy post-menopausal Filipino women seen at the University of Santo Tomas Hospital, Section of Rheumatology, were diagnosed with osteoporosis by central dual-energy X-ray absorptiometry (DXA) technique. Levels of serum 25-hydroxyvitamin D were measured using enzyme-linked immunosorbent assay. Results: The mean age of this population was 70 +/- 8 years, with an average of 22 +/- 10 years since menopause, and mean body mass index (BMI) of 22 +/- 1 kg/m(2). Only 30% (21/70) were on calcium plus vitamin D supplementation. Overall serum 25-hydroxyvitamin D levels ranged from 48-128 nmol/L, with a mean of 87 +/- 20.48 nmol/L. Serum 25-hydroxyvitamin D levels were divided as follows: 80-140 nmol/L (adequate), 25-79 nmol/L (inadequate/insufficient), and < 25 nmol/L (deficient). Sixty-four percent (45/70) of subjects had adequate levels while 36% (25/70) had inadequate levels of 25-hydroxyvitamin D. There were no Subjects with deficient levels of 25-hydroxyvitamin D. Fischer's exact test did not show a significant association between BMD and 25-hydroxyvitamin D (P = 0.4804). Conclusion: Among this group of women with post-menopausal osteoporosis, only 36% had insufficient levels of 25-hydroxyvitamin D, with none of the subjects having deficient 25-hydroxyvitamin D levels. The majority (64%) had normal serum 25-hydroxyvitamin D levels - comparatively higher than that reported in the literature. These results suggest the possible contribution of factors other than vitamin D deficiency in post-menopausal Filipino women with osteoporosis.