Concentrations of vitamin C, vitamin B12 and folic acid in patients treated with hemodialysis and on-line hemodiafiltration or hemofiltration

Objective. Uncertainty has arisen as to whether vitamin supplements are needed by dialysis patients, in particular those treated by means of hemofiltration or hemodiafiltration using highly permeable (high-flux) filters. We therefore measured the concentrations of vitamin C, cobalamin (vitamin B12) and folic acid in conventional (low-flux) dialysis patients and in those receiving on-line treatment (hemofiltration or hemodiafiltration). Material and methods. Plasma (P-) ascorbate, serum (S-) cobalamin and S- folate concentrations were measured before and after a treatment session in 15 patients treated with low-flux hemodialysis and in 14 treated with on-line hemofiltration or hemodiafiltration. The patients' vitamin supplementations were also recorded. Results. P- ascorbate concentrations were lowered by 51% and 53% in the hemodialysis and on-line groups, respectively after treatment and this reduction was significant (p<0.001). Concentrations below the reference values were found in 12/14 patients not receiving vitamin C supplementation. S- cobalamin did not decrease in the hemodialysis or on-line groups. S-folates did not change significantly in the hemodialysis or filtration groups. Patients without folacin supplementation had low values. Conclusions. P- ascorbate was reduced by both dialysis and filtration treatments. Neither S- cobalamin nor S- folate were reduced by dialysis or filtration treatments.