Serum bone gla-protein in osteoporosis treated with 1α-hydroxyvitamin D₃ for more than five years

It has been reported that 1,25-dihydroxyvitamin D₃ increases serum bone Gla-protein (BGP) in a short period in osteoporotic patients as well as in normal subjects. There have been, however, no reports on serum BGP in osteoporotic patients under long term treatment with 1α-hydroxyvitamin D₃. We measured serum BGP in 11 osteoporotic women treated with 1α-hydroxyvitamin D₃ and calcium for 5-12 years, 8.4 years on average. Bone mineral density of distal radius was assessed by single photon absorptiometry. Other biochemical parameters such as serum alkaline phosphatase, fasting urinary hydroxyproline/creatinine and calcium/creatinine were also measured. Serum BGP levels were 6.25±0.36ng/ml (mean±S.E.), being all within the normal range (6.2±3.86ng/ml). We found no significant correlation between serum BGP and other biochemical parameters. Significant correlation was found neither between serum BGP and period of treatment nor between serum BGP and bone mineral density. Our result that serum BGP is within the normal range in osteoporotic patients whose bone mineral density has been maintained by long-term treatment suggests the normal bone turnover in these patients.