Vitamin K, vertebral fractures, vascular calcifications, and mortality: VItamin K Italian (VIKI) dialysis study.

Abstract

Vitamin K (vitamin K1 or phylloquinone and vitamin K2, a series of menaquinones [MKs]) is involved in the production of bone and matrix amino acid γ-carboxy-glutamic acid (Gla) proteins, regulating bone and vascular calcification. Low vitamin K concentrations are associated with increased risks of fractures and vascular calcification, and frequent complications in hemodialysis patients. We carried out an observational study to establish the prevalence of vitamin K deficiency and to assess the relationship between vitamin K status, vertebral fractures, vascular calcification, and survival in 387 patients on hemodialysis for ≥1 year. We determined plasma levels of vitamin K compound, bone-Gla-protein, matrix-Gla-protein, and routine biochemistry. Vertebral fractures (reduction in vertebral body height by ≥20%) and aortic and iliac calcifications were also investigated in a spine (D(5) -L(4)) radiograph. Three-year patient survival was analyzed. Important proportions of patients had deficiency of MK7 (35.4%), vitamin K1 (23.5%), and MK4 (14.5%). A total of 55.3% of patients had vertebral fractures, 80.6% had abdominal aorta calcification, and 56.1% had iliac calcification. Vitamin K1 deficiency was the strongest predictor of vertebral fractures (odds ratio [OR], 2.94; 95% confidence interval [CI], 1.38-6.26). MK4 deficiency was a predictor of aortic calcification (OR, 2.82; 95% CI, 1.14-7.01), whereas MK5 deficiency actually protected against it (OR, 0.38; 95% CI, 0.15-0.95). MK7 deficiency was a predictor of iliac calcification (OR, 1.64; 95% CI, 1.03-2.60). The presence of vertebral fractures was also a predictor of vascular calcifications (OR, 1.76; 95% CI, 1.00-3.08). Increased alkaline phosphatase and C reactive protein (CRP), age, and cerebrovascular events were predictors of mortality. Our study suggests that the vitamin K system may be important for preserving bone mass and avoiding vascular calcification in hemodialysis patients, pointing out a possible role of vitamin K in bone and vascular health. Based on our results, we suggest that the general population should also be studied for vitamin K deficiency as a possible cause of both vertebral fractures and vascular calcification.

• Authors: Maria Fusaro, Marianna Noale, Valentina Viola, Francesco Galli, Giovanni Tripepi, Nicola Vajente, Mario Plebani, Martina Zaninotto, Giuseppe Guglielmi, Diego Miotto, Luca Dalle Carbonare, Angela D'Angelo, Agostino Naso, Cristina Grimaldi, Davide Miozzo, Sandro Giannini, Maurizio Gallieni, VItamin K Italian (VIKI) Dialysis Study Investigators
• Journal: Journal of bone and mineral research : the official journal of the American Society for Bone and Mineral Research (J Bone Miner Res) Vol. 27 Issue 11 Pg. 2271-8 (Nov 2012) ISSN: 1523-4681 [Electronic] United States
• PMID: 22692665 (Publication Type: Journal Article, Multicenter Study)
• Copyright: Copyright © 2012 American Society for Bone and Mineral Research.

Chemical References

• Vitamin K

Topics

• Adult
• Aged
• Case-Control Studies
• Cohort Studies
• Female
• Humans
• Italy (epidemiology)
• Logistic Models
• Male
• Middle Aged
• Renal Dialysis
• Spinal Fractures (blood, complications, mortality)
• Survival Analysis
• Vascular Calcification (blood, complications, mortality)
• Vitamin K (blood)