NO DIRECT EVIDENCE OF INCREASED LIPID-PEROXIDATION IN HEMODIALYSIS-PATIENTS

Lipid peroxidation, as measured by the thiobarbituric acid test, has b een reported to have increased in hemodialysis (HD) patients, even tho ugh the test has low specificity in vivo. Conjugated diene fatty acid (CDFA) hydroperoxides are formed during lipid peroxidation, but not al l conjugated dienes (CD) detected in humans originate from lipid perox idation: octadeca-9,11-dienoic acid, a nonhydroperoxide CD derivative of linoleic acid (CDLA), has a dietary origin. We evaluated CDFA hydro peroxides, CDLA and linoleic acid, using high-performance liquid chrom atography, in lipids extracted from plasma, adipose tissue and RBC mem branes obtained from 25 patients treated with HD, 16 patients treated with hemodiafiltration (HDF) and 29 controls. No differences in the le vels of CDFA hydroperoxides and linoleic acid were seen in any of the groups. Concentrations of CDLA were found to be significantly high in the adipose tissue and low in the RBC membranes of HD patients. HDF-tr eated patients showed the same results as HD patients. No direct evide nce of increased lipid peroxidation was found in HD patients. This doe s not exclude the possibility that lipid peroxidation is increased and escapes direct detection due to the body's homeostatic control elimin ating the increased production of hydroperoxides. Both HD- and HDF-tre ated patients showed a significant change in CDLA concentrations, eith er in the adipose tissue, or in the RBC membranes. These dietary CD ma y be mistaken for markers of lipid peroxidation by conventional method ologies.