The elevation of undercarboxylated osteocalcin (ucOC) means vitamin K insufficiency is significantly increased in elderly women, and is associated with high skeletal turnover, low BMD, and increased risk of osteoporotic fracture. The objective of the present study was to find out the level of ucOC and the prevalence of vitamin K deficiency in elderly Thai women. The upper limit of normal premenopausal ucOC level was 2.314 ng/ml, represented the cut-off level for vitamin K deficiency, 39.1% of elderly women had serum ucOC concentration above this level. Women with high serum ucOC level had a significantly lower BMD of ultradistal radius, distal 1/3 of radius and 25(OH)D level, higher serum PTH and alkaline phosphatase activity than women with a normal ucOC (p<0.05).
Serum ucOC was correlated positively with PTH (r = 0.411, p<0.001), modest negatively with serum 25(OH)D (r = -0.17, p=0.013). The ucOC level of urbanized elderly was higher than that of rural elderly. It was concluded that vitamin K deficiency is one of the risks of osteoporosis with high prevalence in the Thai elderly especially urbanized ones, the supplement of vitamin K should be recommended in Thai osteoporotic patients especially the urbanized elderly.

Keywords: Undercarboxlylated Osteocalcin, UOC, UcOC