Folic acid and pyridoxal-5'-phosphate losses during high-efficiency hemodialysis in patients without hydrosoluble vitamin supplementation.
OBJECTIVE
To determine the serum status in folate, pyridoxal-5'-phosphate (the active moiety of pyridoxine), cobalamin, and total homocysteine of chronic dialysis patients not routinely supplemented with B-complex vitamins and to evaluate induced intradialytic losses during high-efficiency hemodialysis.


METHODS
A cross-sectional study.


METHODS
A university medical center providing tertiary care.


METHODS
Thirty-six chronic dialysis patients (23 men and 13 women, mean age 57+/-13 years) treated since 3.8+/-2.2 years by hemodialysis and not supplemented with hydrosoluble vitamins.


METHODS
Thrice-weekly hemodialysis was performed using CT-190G (Baxter, IL) or F-20 (Hospal, St-Leonard, Canada) reused dialyzers with a mean blood flow rate of 371+/-40 mL/min, a dialysate flow rate of 500 mL/min, and a mean session time of 3.7+/-0.4 hours. Prehemodialysis serum vitamin B(12) and homocysteine, and predialysis and postdialysis serum folate, pyridoxal-5'-phosphate, and urea were measured. Blood-side folate and pyridoxal-5'-phosphate clearances were calculated.


RESULTS
Predialysis serum total homocysteine was above normal in all patients, with values ranging from 14.4 to 158.0 micromol/L (mean 40.2+/-29.6 micromol/L, median 33.5 micromol/L). Whereas the majority, 21 patients, had evidence of coronary, cerebrovascular, and/or peripheral vascular diseases, there was no difference in total homocysteine in patients with or without vascular disease (respectively, 40.8+/-37.0 micromol/L v 39.4+/-15.1 micromol/L, P = NS). Predialysis serum concentrations of pyridoxal-5'-phosphate were reduced in 20 patients (56%) and were in the lower normal range for 14 patients. Predialysis and postdialysis serum folate concentrations were 12.4+/-6.1 nmol/L and 8.6 +/- 3.6 nmol/L, whereas predialysis and postdialysis serum pyridoxal-5'-phosphate concentrations were 11.1+/-7.5 nmol/L and 8.0 +/-5.9 nmol/L. Percent reduction ratios were 68.4% +/- 6.6% for urea, 26.3%+/-16.0% for folates, and 27.9%+/-14.2% for pyridoxal-5'-phosphate. Blood-side clearances reached 134.7+/-22.2 mL/min for folates and 54.4+/-38.2 mL/min for pyridoxal-5'-phosphate. There was no significant difference in predialysis serum folate and pyridoxal-5'-phosphate in patients with or without evidence of vascular disease.


CONCLUSIONS
This study confirms that: (1) total serum homocysteine levels are very high in chronic hemodialysis patients not supplemented with B-complex vitamins; (2) folate is significantly cleared or lost during high-efficiency hemodialysis; and (3) pyridoxal-5'-phosphate, the active moiety of pyridoxine, is depleted in most chronic hemodialysis patients without supplementation and that high-efficiency hemodialysis contributes to its depletion.
Leblanc
M
M
Nephrology and Biochemistry Department, Maisonneuve-Rosemont Hospital and Guy-Bernier Research Center, University of Montreal, Montreal, Canada.
Pichette
V
V
Geadah
D
D
Ouimet
D
D
D003430:Cross-Sectional Studies; D019587:Dietary Supplements; D005260:Female; D005492:Folic Acid / Q000097:blood*; D006710:Homocysteine / Q000097:blood; D006801:Humans; D007676:Kidney Failure, Chronic / Q000097:blood / Q000628:therapy*; D008297:Male; D008875:Middle Aged; D011732:Pyridoxal Phosphate / Q000097:blood*; D006435:Renal Dialysis / Q000009:adverse effects*; D012995:Solubility; D014803:Vitamin B Complex / Q000008:administration & dosage* / Q000627:therapeutic use
D006710:Homocysteine; D014803:Vitamin B Complex; D011732:Pyridoxal Phosphate; D005492:Folic Acid