The effect of short-term low-energy ultraviolet B irradiation on bone mineral density and bone turnover markers in postmenopausal women with osteoporosis: A randomized single-blinded controlled clinical trial

Abstract

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)D 3 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)D 3 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.