Suboptimal vitamin K status and its risk factors in a population of C hinese chronic haemodialysis patients

Aims Vitamin K deficiency is known to be common in haemodialysis patients and associates with adverse outcomes in this population, particularly vascular calcification. We aimed to investigate the vitamin K status in a population of C hinese haemodialysis ( HD ) patients. Methods We collected demographic and biochemical data from a population of maintenance HD ( MHD ) patients in our unit and a control group composed of healthy subjects from our outpatient clinic. Fasting serum samples from all subjects were collected for the measurement of known vitamin K ‐dependent proteins i.e. matrix G la protein ( MGP ), osteocalcin ( OC ) and uncarboxylated osteocalcin (uc OC ). We also quantified the fraction of uc OC to total OC (%uc OC ). Differences of these parameters between groups were analyzed and risk factors of vitamin K deficiency based on the definition as per %uc OC were investigated. Results We enrolled 93 MHD patients as a test group and 93 healthy subjects as a control group. There was no significant difference in MGP between groups (4.0 ± 2.8 pg/mL in MHD   vs 4.2 ± 1.2 pg/mL in control; P  = 0.676). Mean %uc OC was significantly greater in the MHD patients as compared to control subjects (76.4 ± 20.0% in MHD   vs 48.56 ± 15.5%; P  < 0.001). Time on dialysis and low‐density lipoprotein cholesterol level appeared to be indicators of vitamin K deficiency, with the former being an independent risk factor. Conclusions Defining Vitamin K deficiency by %uc OC , suboptimal vitamin K levels appear common in C hinese MHD patients. Time on dialysis and LDL cholesterol level predict vitamin K deficiency.