MO730: Markers of Vitamin K Deficiency in Haemodialysis Patients

Abstract BACKGROUND AND AIMS Vitamin K deficiency is a common feature of CKD, leading to impaired bone quality and an increased risk of vascular calcifications. A method to indirectly measure vitamin K status is measuring the blood level of vitamin K dependent proteins (VKDP)- osteocalcin (OC) and matrix GLA protein (MGP). The aim of this study is to correlate the level of OC and MGP with markers of CKD mineral bone disorder (CKD-MBD). METHOD We conducted a single-centre cross-sectional study that included 45 CKD G5D patients (haemodialysis for 6 months–10 years). All patients have been assessed regarding their dialysis status (medical history), we performed analysis before the dialysis session using standard methods blood biochemistry, complete blood count and intact osteocalcin and matrix GLA protein. RESULTS In the studied haemodialysis patients mean OC was 169.06 ± 128.28 ng/mL, while mean MGP was 3285.93 ± 2092.85 pmol/L. No statistically significant correlation has been found between OC and MGP. We found a strong statistically significant correlation of OC with the markers of CKD-MBD such as: iPTH (r = 0.48, P = 0.0007), serum calcium (r = 0.49, P = 0.0005) and serum phosphorus (r = 0.29, P = 0.04). No statistically significant correlation has been found between MGP and the above- mentioned markers. Only 2 out of 45 patients recorded a past history of bone fractures. Regarding the relationship with the nutritional status of the patients, no statistically significant correlations of the assessed VKDP with BMI and serum albumin have been found. However, a strong indirect statistically significant correlation of OC with abdominal circumference was observed (r = –0.43, P = 0.003). There was also a statistically significant correlation of MGP with markers of inflammation (CRP) (r = 0.55, P = 0.004). No statistically significant differences have been found regarding the level of VKDP between patients with and without a history of diabetes mellitus (13/45), coronary heart disease (18/45) stroke (5/45). The group of patients that are currently under treatment with vitamin K antagonists (13 out of 45) showed significantly higher levels of MGP (5693.0 ± 1728.64 versus 2276.5 ± 1232.54 pmol/L; P < 0.01). Treatment with non-calcium-based phosphate binders (20 patients) was associated to significantly higher levels of MGP compared with treatment with calcium-based phosphate binders (15 patients) (4089.2 ± 2045.79 versus 2134.86 ± 1944.63 pmol/L; P = 0.019). Treatment with vitamin D receptor activator-paricalcitol (20 patients) was associated to significantly increased levels of MGP (4224.55 ± 2162.32 versus 2503.75 ± 1709.31 pmol/L; P = 0.005). CONCLUSION In our study, we found that vitamin K deficiency, measured indirectly using the level of VKDP is associated to CKD-MBD, could be influenced by features of malnutrition-inflammation. The use of medications such as phosphate binders that reduce vitamin K absorbtion, vitamin D that increases vitamin K requirements and also vitamin K antagonists, seems to have an influence on the blood level of VKDPs.