Effect of high parathyroid hormone level on bone mineral density in a vitamin D-sufficient population: Korea National Health and Nutrition Examination Survey 2008-2010

The detrimental effect of high parathyroid hormone (PTH) on bone has not been adequately evaluated in vitamin D-sufficient Koreans. The aim of this study was to investigate the effect of high PTH on bone mineral density (BMD) in such a population. A total of 5,403 subjects (2,644 men and 2,759 postmenopausal women; >= 50 years old) were selected from the 2008-2010 Korea National Health and Nutrition Examination Survey (KNHANES). Subjects were divided into four groups according to vitamin D status (<20 and >= 20 ng/mL) and PTH levels (<= 65 and >65 pg/mL). Total hip and spine BMD were evaluated in each group. High PTH level was found in 50% of vitamin D-deficient subjects and 35% of vitamin D-sufficient subjects. In the vitamin D-deficient group, subjects with normal PTH level had higher total hip and spine BMD than those with high PTH after adjusting for multiple confounding factors, regardless of gender. In the vitamin D-sufficient group, only women with high PTH showed lower total hip and spine BMD than those with normal PTH. Multivariable linear regression analysis found that PTH level was independently associated with total hip BMD in vitamin D-sufficient women as well as vitamin D-insufficient women, but no association was found in men. In conclusion, high serum PTH level has an additive detrimental effect on BMD in postmenopausal women even though they had sufficient vitamin D levels.