Carboxylation of osteocalcin in post-menopausal osteoporotic women following vitamin K and D supplementation

The effect of vitamin supplements on bone metabolism indices in patients with osteoporosis has received scant attention in the literature. Over a 2-week period, vitamin supplements of K and K+D were given to 20 post-menopausal osteoporotic women with previous Colles fractures. Osteoporosis was confirmed by bone mass measurements that demonstrated that broadband ultrasound attenuation (os calcis) was almost as discriminatory as dual energy X-ray absorptiometry (spine and hip) in Colles fracture patients compared with matched controls. Vitamin K corrected the carboxylation defect in osteocalcin and while less marked 4 weeks later, the improvement was still detectable. The result after K+D was similar. The level of carboxylation became the same as in premenopausal women. Total osteocalcin level (bound) osteocalcin. While there was vitamin K correctable undercarboxylation of osteocalcin, simultaneously there was no evidence of undercarboxylation of prothrombin.