Background: Considering the importance of removal of these solutes in chronic renal failure patients, this study was carried out to evaluate the effect of increasing ultrafiltration on clearance of middle molecules in low-flux hemodialysis in Kashan, 2005.

Materials and Methods: Twenty one hemodialysis patients, 11 women and 10 men, were enrolled to this clinical before-after study. At the first stage the patients were dialyzed with ultrafiltration equal to their dry body weight. At the second stage two liters was added to the ultrafiltration and clearance of each solute was calculated in both stages. Data were analyzed using SPSS software and square T test.

Results: T here was a significant difference in clearance of ß2-microglobulin and vitamin B12 in second stage in comparison with the first one (p<0.03, p<0.001), res pectively. While there was no difference in clearance of small molecules P, BUN, and Cr. (p=0.97, r=0.24, p=0.36). In first hemodialysis KT/V was 1.12 and in the second 1.22.

Conclusion: It was shown that in low-flux hemodialysis the increase in ultrafiltration results in increased clearance of middle molecules. Ultrfiltration increase also improve, the adequacy of hemodialysis but it doesn’t affect removal of small molecule.