Efeito da hemodiálise sobre a biodisponibilidade dos ácidos graxos livres em pacientes com insuficiência renal

Abstract

Non-esterified fatty acids (NEFAs) are transported in the blood bound to albumin (AB), which avoids events of lipotoxicity. Circulating NEFAs are elevated in diseases such as sepsis and renal failure, being toxic to cells, causing apoptosis and necrosis. Our objective was to evaluate the effect of hemodialysis (HD) on serum levels of NEFAs in two groups of patients: acute renal failure (ARF) due to sepsis and chronic renal failure (CKD). We also intend to apply a functional test for albumin that evaluates the degree of saturation of albumin by NEFAs. Methods: Prospectively, AB and NEFAs were measured in the same serum, collected pre- and post-HD, from 20 patients from each group. The NEFAs/albumin molar ratios were compared to those obtained in healthy volunteers (n = 15). Values of the total and the fractions of serum NEFAs (myristic (C14:0), palmitic (C16:0), stearic (C18:0), palmitoleic (C16:1), oleic (C18:1) and linoleic)) were determined by HPLC. Conventional hemodialysis and/or prolonged hemodialysis were performed with polysulfone membranes. By the isoelectric focusing method (IF) we determined the migration pH and the protein band density. Results: The respective mean AB concentrations in the ARF, CKD and control groups were 319±113, 443±137 and 647±126µM. Total NEFAs with increased pre-HD values in the ARF and CKD groups, as well as the respective NEFAs/AB (3.91±0.32 and 2.99±0.27), control (0.38±0.03). After HD the NEFAs decreases about 30% in both groups. NEFAs/AB also decreased significantly to 2.5±0.2 (ARF) and 2.16±0.27 (CKD). By IF, pH ranged after HD in both groups (ARF 5,206±0,03 for 5,347±0,02, CKD 5,266±0,03 for 5,413±0,02) and sample densities reduced by about 30%. Conclusion: Hemodialysis reduced the serum bioavailability of NEFAs and contributed to restore the NEFAs/AB molar balance. The FI showed a good correlation between pH and NEFAs/AB and may be useful to evaluate AB saturation in critically ill patients. Therefore, HD is effective in the clearance of serum NEFAs, with potential for prevention of lipotoxicity in patients with acute and chronic renal failure.