Vitamin K supplementation and arterial calcification in dialysis: results of the double-blind, randomized, placebo-controlled RenaKvit trial

Karin Levy-Schousboe, Marie Frimodt-Møller, Ditte Hansen, Christian Daugaard Peters, Krista Dybtved Kjærgaard, Jens Dam Jensen, Charlotte Strandhave, Hanne Elming, Carsten Toftager Larsen, Hanne Sandstrøm, Claus Lohman Brasen, Anne Schmedes, Jonna Skov Madsen, Niklas Rye Jørgensen, Jens Brøndum Frøkjær, Niels Erik Frandsen, Inge Petersen, Peter Marckmann

Abstract

Background: Arterial calcification is associated with cardiovascular mortality in dialysis patients. Active matrix Gla protein (MGP) is a vitamin K-dependent inhibitor of arterial calcification. Elevated plasma concentrations of inactive MGP, i.e. dephosphorylated-uncarboxylated MGP (dp-ucMGP), are prevalent in dialysis patients. MGP inactivity might contribute to arterial calcification. We investigated whether vitamin K supplementation had an effect on arterial calcification in chronic dialysis patients.

Methods: In a 2-year, double-blind, placebo-controlled intervention trial, 48 dialysis patients were randomized to vitamin K [menaquinone-7 (MK-7), 360 µg daily] or placebo. MK-7 in serum and dp-ucMGP in plasma were used to assess vitamin K status. Carotid-femoral pulse wave velocity (cfPWV) and scores of coronary arterial calcification (CAC) and abdominal aortic calcification (AAC) were used to assess arterial calcification.

Results: Thirty-seven participants completed Year 1, and 21 completed Year 2. At Year 2, serum MK-7 was 40-fold higher, and plasma dp-ucMGP 40% lower after vitamin K supplementation compared with placebo {mean dp-ucMGP difference: -1380 pmol/L [95% confidence interval (CI) -2029 to -730]}. There was no significant effect of vitamin K supplementation on cfPWV [mean difference at Year 2: 1.2 m/s (95% CI -0.1 to 2.4)]. CAC Agatston score increased significantly in vitamin K supplemented participants, but was not significantly different from placebo [mean difference at Year 2: 664 (95% CI -554 to 1881)]. AAC scores increased in both groups, significantly so within the placebo group at Year 1, but with no significant between-group differences.

Conclusions: Vitamin K supplementation improved vitamin K status, but did not hinder or modify the progression of arterial calcification in dialysis patients.

OriginalsprogEngelsk
TidsskriftClinical kidney journal
Vol/bind14
Udgave nummer9
Sider (fra-til)2114-2123
Antal sider10
ISSN2048-8505
DOI
StatusUdgivet - sep. 2021

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