The aminothiol redox status in haemodialysis patients does not improve with folate therapy

Patients on haemodialysis suffer from high cardiovascular morbidity and mortality, and oxidative stress may play a role in the pathophysiology of cardiovascular disease in these patients. Hyperhomocysteinemia is common in dialysis patients and may have pro-oxidant effects. Moreover, the redox status of the major plasma aminothiols (homocysteine [Hcy], cysteine and cysteinylglycine) may be regarded as a biomarker of oxidative stress. In the present study, we investigated the aminothiol redox status during a period of homocysteine-lowering therapy with folinic acid.

In the first part of the study, 32 stable patients receiving maintenance haemodialysis were compared with 32 reference subjects. In the second part, the patients were given folinic acid intravenously for 3 months.

Before intervention with folinic acid, the patients had elevated concentrations of all redox species of Hcy. The aminothiol redox ratios were low. Folinic acid therapy lowered the concentrations of all Hcy redox species; however, the redox ratios did not improve.

The low aminothiol redox ratios indicate the presence of oxidative stress in haemodialysis patients. Therapy with folinic acid lowered total Hcy concentrations, but did not improve the redox status. Thus, hyperhomocysteinemia appears to be of little importance in regard to the total level of oxidative stress in uraemia.