Vitamin K supplementation and arterial calcification in dialysis: results of the double-blind, randomized, placebo-controlled RenaKvit trial
Open Access
- 28 January 2021
- journal article
- research article
- Published by Oxford University Press (OUP) in Clinical Kidney Journal
- Vol. 14 (9), 2114-2123
- https://doi.org/10.1093/ckj/sfab017
Abstract
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. 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. 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. Vitamin K supplementation improved vitamin K status, but did not hinder or modify the progression of arterial calcification in dialysis patients.Keywords
Funding Information
- The Danish Society of Nephrology
- The Danish Kidney Association
- The Region Zealand Research Foundation
- Kappa Bioscience AS
- Aase and Ejnar Danielsen’s Foundation
- Helen and Ejnar Bjørnow’s Foundation
- The Beckett Foundation and Karen Elise Jensen’s Foundation
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