This study aims at finding the optimal dose of Vitamin K2 supplementation in hemodialysis patients.

During the past few years evidence is emerging for a role of Matrix Gla Protein (MGP) as one of the most powerful inhibitors of vascular calcification (Shurgers LJ et al. Thromb Haemost 2008; 100: 593-603). MGP is a Vitamin K dependent protein. This means that he presence of Vitamin K2 is required to promote the gamma-carboxylation process turning MGP in its carboxylated and active form. Recent data show that dp-uc MGP correlates well with Vitamin K status (Cranenburg CM et al. Thrombosis and Haemostasis 2010; 104/4: 811-822).

It is widely recognized that patients with renal insufficiency treated with hemodialysis are prone to accelerated vascular calcification resulting in excess cardiovascular morbidity and mortality (Goodman WG et al. N Engl J Med 2000; 342: 1478-1483).

Consequently, the administration of Vitamin K2 supplements may protect hemodialysis patients against accelerated vascular calcification by enhancing the gamma-carboxylation process of MGP. However, the optimal dose of Vitamin K2 required to achieve these results remains to be defined

Inclusion Criteria:

• age ≥18 year
• signed informed consent
• end stage renal disease treated with chronic hemodialysis at least three times a week

Exclusion Criteria:

• coumarin treatment
• known intestinal malabsorption
• inability to take oral medication
• medical conditions with a considerable probability for death within 2 months