#1943 The association of uncarboxylated, non-phosphorylated Matrix Gla protein with arterial stiffness in hemodialysis and peritoneal dialysis patients

Abstract Background and Aims Vitamin K deficiency has been identified as a marker of vascular calcification AND STIFNESS and an independent cardiovascular risk factor in hemodialysis (HD) and peritoneal dialysis (PD) patients, as the most powerful inhibitor of vascular calcification, Matrix Gla Protein requires vitamin K to become activated. However, until to date, it has not yet been clarified whether hepatic or extrahepatic markers of vitamin K status reflect the arterial status of dialysis patients. In this study we aimed to investigate the association of vitamin K deficiency with arterial stiffness in End-Stage Kidney Disease (ESKD) patients. Method In 42 ESKD patients undergoing either HD or PD, we measured plasma levels of the inactive vitamin-K dependent Matrix Gla Protein (dp-ucMGP) and serum levels of prothrombin (PIVKA-II) as markers of extrahepatic and hepatic insufficiency of vitamin K (CARIM Institute, Maastricht, Netherlands). In these patients we determined arterial stiffness parameters (pulse wave velocity-PWV) by the Mobil-O-Graph device (IEM, Stolberg, Germany). Results Serum PIVKA-II was associated with T2D duration (r = −0.38, p = 0.013), phosphorus levels (r = −0.41, p = 0.009) serum albumin (r = −0.33, p = 0.036) Spearman's rho test, and the type of transporter in PD patients (p = 0.039), Kruskal-Wallis test. Plasma dp-ucMGP was associated with PWV (r = 0.51, p = 0.001), peripheral (r = −0.37, p = 0.016) and central diastolic blood pressure (BP) (r = −0.34, p = 0.026) and age (r = 0.41, p = 0.007), Spearman's rho. Patients with T2DM, history of acute myocardial infarction and those receiving warfarin had significantly increased levels of circulating dp-ucMGP (p = 0.036, p = 0.039 and p 0.0001, respectively, Kruskal-Wallis). Warfarin was associated with a 2.5-fold and a 23-fold increase in dp-ucMGP and PIVKA-II levels, respectively. Stepwise multiple regression analysis showed that PWV (p = 0.001, B = 494, 95% CI: 242-746) was an independent predictor of dp-ucMGP, independent of age, T2T2, history of myocardial infraction and diastolic BP. Conclusion Elevated plasma dp-ucMGP levels (suggesting extrahepatic vitamin K deficiency) were associated with increased arterial stiffness in dialysis patients.