title: Vitamin K-induced changes in markers for osteoblast activity and urinary calcium loss.
abstract: The objective of this study was to identify subjects in whom vitamin K has an effect on markers for calcium and bone metabolism and to detect hitherto-unnoticed correlations between vitamin K-induced changes in these markers. Participants in our studies were apparently healthy women, in whom we measured serum-immunoreactive osteocalcin (irOC) before and after adsorption to hydroxylapatite; total serum alkaline phosphatase (T-AP) and bone-specific alkaline phosphatase (B-AP); and fasting urinary calcium and creatinine. We describe a trial among 145 women who were treated with vitamin K (1 mg/day) for 2 weeks, and a prospective placebo-controlled trial among two groups each of 70 postmenopausal women with a treatment period of 3 months. It turned out that in elderly women vitamin K induced increased levels of serum irOC with a high affinity for hydroxylapatite (irOCbound), whereas that with low affinity (irOCfree) remained unaffected. In placebo-treated women the ratio irOCfree/irOCbound shifted from 0.38 to 0.65 around the 50th year of age. This shift was not found in vitamin K-treated women. After 3 months of treatment the vitamin K-induced changes in irOCbound were correlated with changes in B-AP, whereas irOCfree was correlated to urinary calcium excretion. In fast losers of urinary calcium vitamin K induced a 30% decrease of calcium excretion. The hypothesis is put forward that irOCbound may be a marker for bone formation, that serum irOCfree may be a marker for bone resorption, and that the serum irOCfree/irOCbound ratio may become a marker for skeletal remodeling.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Biochemistry, University of Limburg, Maastricht, The Netherlands.
authors.forename: M H
authors.initials: MH
authors.lastname: Knapen
authors.forename: K S
authors.initials: KS
authors.lastname: Jie
authors.forename: K
authors.initials: K
authors.lastname: Hamulyák
authors.forename: C
authors.initials: C
authors.lastname: Vermeer
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000378:metabolism; D000469:Alkaline Phosphatase / Q000032:analysis / Q000097:blood; D015415:Biomarkers / Q000032:analysis; D001842:Bone and Bones / Q000201:enzymology / Q000378:metabolism; D002118:Calcium / Q000652:urine*; D005260:Female; D006801:Humans; D006882:Hydroxyapatites / Q000378:metabolism; D008875:Middle Aged; D010006:Osteoblasts / Q000378:metabolism / Q000502:physiology*; D015675:Osteocalcin / Q000097:blood*; D011446:Prospective Studies; D013997:Time Factors; D014812:Vitamin K / Q000494:pharmacology*
chemical_list: D015415:Biomarkers; D006882:Hydroxyapatites; D015675:Osteocalcin; D014812:Vitamin K; D000469:Alkaline Phosphatase; D002118:Calcium