Influence of haemodialysis on plasma total homocysteine concentration

Background. The high prevalence of hyperhomocysteinaemia in uraemic patient s is of interest because of the cardiovascular risk associated with increas ed plasma total homocysteine (tHcy) concentration. Treatment with folic aci d lowers tHcy in haemodialysis patients, however, in most patients not to n ormohomocysteinaemic levels. With possible tHcy-lowering modifications in m ind, we studied the influence of standard haemodialysis on tHcy. Methods. In 56 folate-loaded haemodialysis patients, tHcy and parameters of dialysis adequacy were measured. In six patients, interdialytic curves of tHcy and serum creatinine concentrations were obtained and in five patients , the amount of homocysteine (Hcy) in dialysate was determined. Results. tHcy(21.8 +/- 14.4 mu mol/l) correlated significantly with Kt/V (r = 0.32, P < 0.05), total Kt/V (r = 0.29, P < 0.05), nPCR (r = 0.30, P < 0. 05) and serum concentrations of albumin (r = 0.28, P < 0.05) and cobalamine s (r = -0.27, P < 0.05). In a multiple linear regression analysis, only ser um albumin concentrations significantly predicted tHcy (r = 0.34, P < 0.05) . During dialysis, tHcy decreased by 28% and remained constant for at least 8 h after treatment. The amount of Hey recovered in dialysate was 63 mu mo l (12-158 mu mol). There was no difference in tHcy between those who had re sidual renal function and those who had not. Conclusions. The direct relationship between tHcy and Kt/V seemed to be med iated by the serum albumin concentration. The shape of the interdialytic tH cy curve suggested facilitated Hey removal for at least 8 h after dialysis possibly due to reduced levels of inhibitory activities against relevant en zyme(s). The dialysed amount of Hey did not seem to contribute significantl y to Hey removal. Thus, modifications of standard dialytic regimens are not likely to be effective from a tHcy-lowering point of view whereas convecti ve procedures such as haemofiltration or haemodiafiltration might be more e ffective.