Effects of vitamin K and oral anticoagulants on urinary calcium excretion

Abstract

In a subgroup of postmenopausal women vitamin K induced a decrease of the urinary calcium loss. This effect was significant (P < 0.0001) in the so-called fast losers of calcium (calcium/creatinine ratio > 0.5). To find out whether vitamin K antagonists would have an opposite effect, a study was started among 141 persons on long-term oral anticoagulant therapy. In this population the number of fast losers was recorded, and compared to that in a group of age- and sex-matched non-treated controls. Notably in young men the fraction of fast losers was significantly higher in the anticoagulant-treated group than in the control group (25 v 0%, P < 0.02). Differences between treated and nontreated groups may also be found in other markers for calcium and bone metabolism, notably in serum osteocalcin concentration and in urinary hydroxyproline excretion. The conclusion of our study is that oral anticoagulant treatment must be regarded as a potential risk factor for a high loss of urinary calcium.

Vitamin K supplementation reduces serum concentrations of under-γ-carboxylated osteocalcin in healthy young and elderly adults

“…This occurred in healthy subjects who had normal coagulation variables and whose baseline phylloquinone concentrations were similar to those reported previously in healthy adults (1,2,23), showing that usual dietary practices provide inadequate phylloquinone to allow maximal osteocalcin ␥-carboxylation. Less than maximal ␥-carboxylation of vitamin K-dependent proteins has been suggested to be a more sensitive definition of vitamin K deficiency than are coagulation measures (2,(24)(25)(26). However, whether the high prevalence of vitamin K insufficiency observed in this study has physiologic relevance is unclear.…”

A high phylloquinone intake is required to achieve maximal osteocalcin γ-carboxylation,,

“…This study suggests that daily doses of 1000 g phylloquinone may be optimal in studies evaluating the skeletal effects of vitamin K. Previous skeletal studies used supplemental phylloquinone doses of 200 (34), 1000 (20,35,36), or 10 000 (37) g/d. Thus, whereas most previous studies used optimal amounts of phylloquinone, 200 g/d might be insufficient.…”

Effects of Menatetrenone on the Decrease in Calcium Balance Induced by Vitamin K-Deficient Diet and Sodium Loading in Rats.

“…A vitamin K2 homologue, menatetrenone (MK-4), was shown to be effective in ameliorating bone loss induced by ovari ectomy in rats (4), and the clinical efficacy of MK-4 was demonstrated in a double-blind multi-center comparative study with alfacalcidol in patients with postmenopausal and senile osteoporosis (5). Vitamin K, prevented in creases in urinary calcium excretion in rats that received vitamin K-deficient feed and antibiotics (6) and in postmenopausal women (7). Depressed levels of menaqui nones were also shown to induce fractures in osteoporotic patients (8).…”