Dogma disputed: postdialysis increase of aminotransferase values cannot be attributed to an inhibitor removal by hemodialysis.

The objective of this study was to assess changes of aspartate aminotransferase (AST [serum glutamic oxalacetic transaminase]) and alanine aminotransferase (ALT [serum glutamic pyruvic transaminase]) values after a hemodialysis (HD) session. Aspartate aminotransferase and ALT serum values were measured before and after a 4 h HD session in 37 stable patients (group A), before and after a 3.5 h isovolemic HD (IVHD, with a zero ultrafiltration rate) session in eight patients (group B), as well as before and after a session of "isolated ultrafiltration" (IUF) in eight more patients (group C). In group A, mean predialysis AST and ALT serum values that were 16.4 ± 4.3 and 16.0 ± 5.5 IU/L, increased to 20.1 ± 5.4 and 17.7 ± 6.2 IU/L, respectively (p < 0.0001, comparing pre- to postdialysis values, for both). When the postdialysis values were corrected for hemoconcentration induced by ultrafiltration, no differences were found in ALT values. However, postdialysis-corrected AST values (mean 17.7 ± 4.4 IU/l) remained higher compared with predialysis values (p < 0.001). The AST/ALT ratio was 1.13 ± 0.4 for predialysis values and 1.26 ± 0.5 for postdialysis values (p < 0.0001). Predialysis mean serum AST and ALT values did not show any difference after the 3.5 h IVHD sessions (group B), but increased significantly (p < 0.02) after the removal of 1.7 ± 0.2 L of fluid by IUF (group C). In chronic HD patients, postdialysis serum AST and ALT values increased significantly compared with predialysis values. This increment is mainly due to hemoconcentration induced by ultrafiltration and cannot be attributed to the removal of an aminotransferase inhibitor by HD.

Subtherapeutic serum vancomycin concentrations during on-line hemodiafiltration.

The aim of the study is to study vancomycin serum concentration changes during on-line hemodiafiltration (OL-HDF) and determine whether administration of vancomycin during the last hour of OL-HDF provides therapeutic serum concentrations. Vancomycin was administered intravenously at a dose of 15 mg/kg to 17 chronic hemodialysis patients who were enrolled into two study groups (A and B). In group A patients (n = 11), vancomycin was administered immediately postdialysis. Forty-three hours later, a 4-hour OL-HDF session was performed. Blood samples (S) for vancomycin measurement were drawn before, during, and after the session. In group B patients (n = 6), vancomycin was administered during the last hour of a 4-hour OL-HDF session on Monday. Vancomycin serum concentrations were measured postdialysis, as well as before and after the next two dialysis sessions of the week. In group A patients, mean vancomycin concentrations were reduced by 50% (S(pre): 10.2 ± 1.4 µg/ml, S(post): 5.0 ± 0.9 µg/ml). Vancomycin dialysance was 74.6 ± 29.3 ml/min, while the volume of distribution was 0.42 L/kg. In group B patients, mean vancomycin concentrations before the beginning of Wednesday and Friday dialysis sessions were 3.1 ± 0.7 and 1.4 ± 0.4 µg/ml, respectively. Postdialysis administration of vancomycin followed by OL-HDF resulted in a 50% reduction of vancomycin serum concentrations. Administration during the last treatment hour of OL-HDF results in subtherapeutic vancomycin serum concentrations over the course of the subsequent inter- and intradialytic intervals.