Daily intake and serum concentration of menaquinone-4 (MK-4) in haemodialysis patients with chronic kidney disease.

OBJECTIVES: Decreased concentration of menaquinone-4 (MK-4) seems to be an important risk factor of vascular calcification in haemodialysis (HD) patients. Optimal dietary intake, as well as serum MK-4 reference range, in HD has not been determined, yet. The aim of the present study was to assess daily vitamin K1 and MK-4 intakes and their relation to serum MK-4 concentration in HD patients. DESIGN AND METHODS: Daily vitamin K1 and MK-4, micro- and macronutrients and energy intakes were assessed using 3-day food diary completed by patients and serum MK-4 concentration was measured by HPLC [limit of quantification (LOQ): 0.055 ng/mL] in 85 HD patients (51 males) and 22 apparently healthy subjects. RESULTS: Daily MK-4 intake was significantly lower (by 29%) among HD, while K1 consumption was similar in both groups. Daily MK-4 intake was associated with fat and protein consumption in HD (r=0.43, p<0.001 and r=0.33, p=0.004, respectively). In HD serum MK-4 concentration was more frequently below LOQ (in 41% HD and 5% controls, p<0.001) and in those HD with quantifiable values was lower than in the controls (by 42%). The correlations between MK-4 concentrations and both MK-4 and K1 daily intakes were weaker in HD (r=0.38 and r=0.30 respectively) than in the control group (r=0.47 and r=0.45, respectively). In multiple regression analysis the variability of serum MK-4 concentrations in HD patients was explained by its daily intake. CONCLUSIONS: Decreased serum MK-4 concentration in HD patients is caused by lower dietary MK-4 intake, mainly due to diminished meat consumption, and in addition, probably reduced K1 conversion.