RESUMEN
INTRODUCTION: The importance of vitamin D on bone health and osteoporosis was studied by many researchers. The main role of the Vitamin D is to absorb calcium and phosphate and increase bone mineralization. Older people are at an increased risk of the inadequate vitamin D production in the skin because of lower sun exposure and reduced ability of the skin to synthesize vitamin D. OBJECTIVE: The aim of this clinical trial was to evaluate the efficacy and tolerability of short-term (2 weeks) low energy UVB irradiation in postmenopausal women with osteoporosis using bone mineral density and bone turnover markers. METHODS: A three-month, single-blinded, randomized, placebo-controlled clinical trial was conducted at the University hospital in Daegu, Republic of Korea. Fifty-two postmenopausal Korean women (older than 65 years) with osteoporosis were randomly allocated to have either low energy UVB or placebo for 30 minutes a day for two weeks of treatment during winter. Laboratory analysis and physical examination before and 4, 8 and 12 weeks after treatment were carried out and BMD was measured before and 8 and 12 weeks after treatment. The effects of time and treatment interaction between these two groups were evaluated by repeated-measure two-factor analysis, and subgroup analysis was performed to examine UVB effect on the vitamin D insufficient group [serum 25(OH)D3 concentration < 30 ng/mL]. RESULTS: In vitamin D insufficient group, the effect of UVB irradiation on vitamin D and bone ALP as well as additional benefit on bone formation was confirmed. The vitamin D insufficient group showed statistically significant increment in serum 25(OH)D3 compared with the normal group (p < 0.05). However, there was no significant difference between two groups in the other bone turnover markers, such as serum calcium, PTH-C, serum osteocalcin, serum CTX and BMD. CONCLUSION: Low-energy-short-term UVB radiation for postmenopausal women may be of use in vitamin D synthesis. There was a modest benefit in change of bone ALP especially in women with the insufficient vitamin D.