Effect of vitamin K2 supplementation on functional vitamin K deficiency in hemodialysis patients: a randomized trial.

Abstract

BACKGROUND:

Vascular calcification is a predictor of cardiovascular morbidity and mortality. Hemodialysis patients experience severe vascular calcifications. Matrix Gla protein (MGP) is a central calcification inhibitor of the arterial wall; its activity depends on vitamin K-dependent γ-glutamate carboxylation. Uncarboxylated MGP, formed as a result of vitamin K deficiency, is associated with cardiovascular disease. Recent studies suggest poor vitamin K status in hemodialysis patients. We therefore aimed to investigate whether daily vitamin K supplementation improves the bioactivity of vitamin K-dependent proteins in hemodialysis patients, assessed by circulating dephosphorylated-uncarboxylated MGP, uncarboxylated osteocalcin, and uncarboxylated prothrombin (PIVKA-II [protein induced by vitamin K absence II]).

STUDY DESIGN:

Interventional randomized non-placebo-controlled trial with 3 parallel groups.

SETTING & PARTICIPANTS:

53 long-term hemodialysis patients in stable conditions, 18 years or older. 50 healthy age-matched individuals served as controls.

INTERVENTIONS:

Menaquinone-7 (vitamin K(2)) treatment at 45, 135, or 360 μg/d for 6 weeks.

OUTCOMES:

Plasma levels of dephosphorylated-uncarboxylated MGP, uncarboxylated osteocalcin, and PIVKA-II.

MEASUREMENTS:

Plasma levels were assessed using enzyme-linked immunosorbent assays.

RESULTS:

At baseline, hemodialysis patients had 4.5-fold higher dephosphorylated-uncarboxylated MGP and 8.4-fold higher uncarboxylated osteocalcin levels compared with controls. PIVKA-II levels were elevated in 49 hemodialysis patients. Vitamin K(2) supplementation induced a dose- and time-dependent decrease in circulating dephosphorylated-uncarboxylated MGP, uncarboxylated osteocalcin, and PIVKA-II levels. Response rates in the reduction in dephosphorylated-uncarboxylated MGP levels were 77% and 93% in the groups receiving 135 μg and 360 μg of menaquinone-7, respectively.

LIMITATIONS:

Small sample size.

CONCLUSIONS:

This study confirms that most hemodialysis patients have a functional vitamin K deficiency. More importantly, it is the first study showing that inactive MGP levels can be decreased markedly by daily vitamin K(2) supplementation. Our study provides the rationale for intervention trials aimed at decreasing vascular calcification in hemodialysis patients by vitamin K supplementation.

• Authors: Ralf Westenfeld, Thilo Krueger, Georg Schlieper, Ellen C M Cranenburg, Elke J Magdeleyns, Stephan Heidenreich, Stefan Holzmann, Cees Vermeer, Willi Jahnen-Dechent, Markus Ketteler, Jürgen Floege, Leon J Schurgers
• Journal: American journal of kidney diseases : the official journal of the National Kidney Foundation (Am J Kidney Dis) Vol. 59 Issue 2 Pg. 186-95 (Feb 2012) ISSN: 1523-6838 [Electronic] United States
• PMID: 22169620 (Publication Type: Journal Article, Randomized Controlled Trial)
• Copyright: Copyright © 2012 National Kidney Foundation, Inc. Published by Elsevier Inc. All rights reserved.

Chemical References

• Biomarkers
• Calcium-Binding Proteins
• Extracellular Matrix Proteins
• Protein Precursors
• alpha-2-HS-Glycoprotein
• matrix Gla protein
• Osteocalcin
• Vitamin K 2
• acarboxyprothrombin
• Prothrombin

Topics

• Adult
• Aged
• Aged, 80 and over
• Biomarkers (blood)
• Calcium-Binding Proteins (blood)
• Comorbidity
• Dietary Supplements
• Disease Progression
• Dose-Response Relationship, Drug
• Extracellular Matrix Proteins (blood)
• Female
• Humans
• Kidney Diseases (blood, epidemiology, therapy)
• Male
• Middle Aged
• Osteocalcin (blood)
• Prospective Studies
• Protein Precursors (blood)
• Prothrombin
• Renal Dialysis
• Single-Blind Method
• Treatment Outcome
• Vascular Calcification (blood, epidemiology, prevention & control)
• Vitamin K 2 (administration & dosage, therapeutic use)
• Vitamin K Deficiency (blood, drug therapy, epidemiology)
• alpha-2-HS-Glycoprotein (metabolism)