Sevelamer Use, Vitamin K Levels, Vascular Calcifications, and Vertebral Fractures in Hemodialysis Patients: Results from the VIKI Study

ABSTRACT Hyperphosphatemia is a risk factor for vascular calcifications (VCs), which are part of the chronic kidney disease‐mineral and bone disorders (CKD‐MBD). Vitamin K‐dependent proteins such as matrix Gla protein (MGP) and bone Gla proteins (BGP, or osteocalcin) can inhibit VCs and regulate bone mineralization. In this analysis of the Vitamin K Italian (VIKI) study, the relationship between vitamin K status, vertebral fractures (VFs) and VCs in 387 hemodialysis (HD) patients with (N = 163; 42.1%) or without N = 224; 57.9%) sevelamer was evaluated. Levels of vitamin K vitamers K1 and K2 or menaquinones (MK; MK4–7), total and undercarboxylated (uc) forms for both BGP and MGP were determined. Although no differences in clinical characteristics were noted, lower levels of MK4 (0.45 versus 0.6 ng/mL, p = .01) and a greater MK4 deficiency was observed in sevelamer‐treated patients (13.5% versus 5.4%, p = .005). Multivariate logistic regression revealed that MK4 deficiency was associated with sevelamer use (odds ratio [OR] = 2.64, 95% confidence interval [CI] 1.25–5.58, p = .011) and aortic calcification (OR = 8.04, 95% CI 1.07–60.26, p = .04). In the same logistic model, sevelamer amplified the effect of total BGP levels on the odds of VFs in patients with total BGP