DETERMINATION OF SERUM 25-HYDROXY VITAMIN D3 LEVELS IN EARLY POSTMENOPAUSAL IRANIAN WOMEN: RELATIONS TO BONE MINERAL DENSITY AND URINE HYDROXYPROLINE

Vitamin D plays an important role in calcium and phosphorus metabolism as well as bone and teeth growth and maintenance. In the present study, the vitamin D status in postmenopausal Iranian women and its relationship with bone mineral density (BMD) and urine hydroxyproline (OHPr) were determined. The serum levels of 25-hydroxyvitamin D3 (25-OHD3), BMD and OHPr assessed in 85 selected, early postmenopausal women (49-67 yr) referred to the Bone Densitometry Center, Loghman-Hakim Hospital, Tehran. The relations among them were also evaluated. Both 25-OHD3 and OHPr levels were measured for the first time in Iran using HPLC (High Performance Liquid Chromatography) and spectrophotometric methods, respectively. BMD measured with dual energy X-ray absorptiometry in lumbar spine and proximal femur regions. 25-OHD3 levels ranged between 3.8-64.0 ng/ml (mean ± SD, 17.3 ± 11.4ng/ml). Thirty-two subjects (38%) were vitamin D deficient (<12ng/ml). In lumbar spine (L2-L4) BMD measurments, 34% were normal, 39% were osteopenic and 27% were osteoporotic. In femur (total) BMD measurments, 50.6% were normal, 47% were osteopenic and 2.3% were osteoporotic. Urine OHPr/creatinine ratio used as an index for OHPr and ranged between 3.5-51.0 μ mol/mmol (14.8 ± 8.8 μ mol/mmol). There was a significant correlation between 25-OHD3 and spine BMD (r = 0.21, p<0.05), but regarding femur BMD, the correlation was not significant. OHPr had neither a significant correlation with 25-OHD3 nor with spine and femur BMD. We concluded that vitamin D deficiency was evident in early postmenopausal Iranian women and serum 25-OHD3 levels correlated with the spine bone density.