No Benefit of Hemodiafiltration over Hemodialysis in Lowering Elevated Levels of Asymmetric Dimethylarginine in ESRD Patients

BACKGROUND: It has been suggested that hemodiafiltration (HDF) is more efficient than hemodialysis (HD) in lowering plasma levels of the endogenous nitric oxide synthase inhibitor asymmetric dimethylarginine (ADMA), which is a strong and independent predictor of overall mortality in ESRD patients. METHODS/PATIENTS: Twenty ESRD patients (11 women) were studied during both a single online HDF session and a single HD session. In each patient, ADMA, L-arginine, SDMA, beta(2)-microglobulin and urea were measured at several time points. RESULTS: Although HDF was clearly superior to HD in decreasing plasma beta(2)-microglobulin, there was no difference in the elimination characteristics of ADMA. However, HDF but not HD eliminated the nitric oxide synthase substrate L-arginine, making HD superior in increasing the L-arginine/ADMA ratio. CONCLUSION: Neither HD nor HDF sufficiently removes the putative uremic toxin ADMA. The clinical significance of HD better improving the L-arginine/ADMA ratio (parameter of NO production) as compared to HDF needs to be determined.