VITAMIN K2 STATUS IN PATIENTS WITH PRE-DIALYSIS CHRONIC KIDNEY DISEASE

Vitamin K2 plays a key role in calcium homeostasis through activation of VKDP, including matrix Gla protein, a potent inhibitor of vascular calcification. Impaired vitamin K2 status results in increased circulating levels of inactive dephosphorylated uncarboxylated MGP (dp-ucMGP), which serves as a marker for vitamin K2 deficiency. CKD patients are at particularly high risk of vitamin K2 deficiency and its related complications. Purpose: To assess vitamin K2 status indirectly by measuring plasma dp-ucMGP levels in patients with pre-dialysis CKD. Material/Methods: This cross-sectional study included 71 adult Caucasian patients with pre-dialysis CKD stages G1–G4, classified according to KDIGO criteria. Participants were divided into three groups based on estimated glomerular filtration rate (eGFR). Serum creatinine, calcium, inorganic phosphate, and plasma dp-ucMGP levels were measured. Statistical analyses were performed using appropriate parametric and non-parametric tests. Results: Significant differences were observed among the groups in age, renal function parameters, serum calcium, and phosphate levels (p < 0.05). Plasma dp-ucMGP concentrations did not differ significantly between CKD stages. However, when compared with recalculated reference values reported in the literature, dp-ucMGP levels in all groups were elevated, suggesting functional vitamin K2 deficiency. Sex-specific analysis revealed significantly higher dp-ucMGP levels in females with preserved to moderately reduced renal function, while no sex-related differences were observed in advanced CKD. Conclusion: Patients with pre-dialysis CKD demonstrated poor vitamin K2 status, as reflected by elevated dp-ucMGP levels. These findings support growing evidence that vitamin K2 deficiency is common and clinically relevant in the earlytages of CKD.