The association of Vitamin D and Parathyroid Hormone with Bone Mineral Density in Korean Postmenopausal Women

ABSTRACT

BACKGROUND: Osteoporosis results from bone loss due to menopause [estrogen(E) deficiency] and aging. Initial skeletal effect of menopause is accelerated bone resorption with an increase in seurm calcium(Ca) and compensatory but inadequate bone formation. Secretion of parathyroid hormone(PTH) is suppressed at this time. Postmenopausal osteoporosis results in fractures predominantly of trabecular bone, i.e., vertebra. With aging, secondary hyperparathyroidism by low serum Ca and vitamin D deficiency superim poses. Senile osteoporosis produces hip fractures, area of cortical bone. The aim of this study was to- examine the association of vitamin D[25(OH)D] and intact(i) PTH with bone mineral density(BMD) after controlling for suggested confounding factors, and the possibility of low serum vitamin D and high serum iPTH concentration could impact bone loss in Korean postmenopausal women. METHODS: Data from 188 postmenopausal Korean women aged 42 to 69 were analyzed through BMD, serum 25(OH)D, iPTH, Ca, phosphorus(P), alkaline phosphatase(ALP) and clinical characteristics. Factors affecting BMD was determined by Pearson correlation and the relationship between lumbar and femoral neck BMD and vitamin D[25(OH)D] and iPTH was assessed by multiple regression analysis after adjus- ting for suggested confounding factors. RESULTS: Lumbar and femoral neck BMD, serum Ca, P were decresaed and serum iPTH was increased with aging. In Pearson`s correlation, significant contributing factors to lumbar BMD was age, height, weight, menarche, year since menopause(YSM) and ALP. And significant contributing factors to femoral neck BMD was age, height, weight, menarche, YSM and iPTH. No relationship could be demonstrated between serum vitamin D[25(OH)D] and lumbar and femoral neck BMD. How ever, after controlling for potential confounding factors, a correlation was found between vitamin D[25(OH)D] and both of lumbar (p=0.013) and femoral neck BMD(p=0.077). iPTH was inversely related to femoral neck BMD(p=0.004) only in multiple linear regression. CONCLUSION: Serum vitamin D[25(OH)D] was influencing both of vertebral and femoral neck BMD, which suggests a significant role of vitamin D deficiency in the pathogenesis of postmenopausal osteo- porosis. In age related remodeling and loss of bone, increased serum iPTH might have additive role in cortical bone of femur. These findings suggest that vitamin D is very important for optimal bone health and a deleterious effect of increased iPTH on cortical bone loss. Adequate calcium and vitamin D status have to be maintained to prevent osteoporosis in postmenopausal Korean women.