 This study aims to: 1 quantitatively assess parameters of bone calcium balance in healthy postmenopausal Asian women of Chinese descent; 2 assess possible ethnic differences in calcium metabolism by direct comparison of acquired data in Chinese postmenopausal women with those acquired earlier in Caucasian postmenopausal women using the same methodology; 3 assess differences in calcium and strontium metabolism in parallel to evaluate if strontium stable isotopes can be used for tracing bone calcium metabolism qualitatively 