Significance of nitrogen removal mass in uremic patients on different modalities of dialysis therapy

Background and purpose: While most nephrologists use Kt/V values for dialys is prescriptions, some researchers are beginining to view the role of solut e removal mass as an indicator of adequate dialysis. This study, using nitr ogen as a surrogate for solute removal, probed whether solute removal mass can be used as the target of adequate dialysis. Mathematical formulas for e asy bedside calculation of nitrogen removal mass were used to avoid the pro blems associated with direct measurement. Methods: The weekly removal mass of urea nitrogen (M) and the urea generati on rate (G) of 32 conventional hemodialysis (HD) and 21 continuous ambulato ry peritoneal dialysis (CAPD) patients were calculated. All the patients we re anuric, clinically stable, and under adequate dialysis pursuant to eithe r the criterion of the urea index. Kt/V, or clinical requirements. Results: The difference of M-HD (M-HD = 41.9 +/- 9.5 g/week, M-CAPD = 38.8 +/- 11.9 g/week) and G (G(HD) = 3.90 +/- 1.02 mg/min. G(CAPD) = 3.85 +/- 1. 21 mg/min) between the two groups was statistically insignificant (p = 0.11 9 and p = 0.868, respectively). When protein nitrogen leaking through the p eritoneal membrane was considered and added to M-CAPD, nitrogen removal in CAPD patients (M-CAPD' = 42.3 +/- 13.0 g/week) approached that in HD patien ts (p = 0.886). There was no correlation between dialysis dosage and urea r emoval mass in either the CAPD or HD groups. Conclusions: Urea nitrogen removal mass in similar to the protein catabolic rate (PCR) in stable patients. It is meaningful in dialysis evaluation onl y when it is used simultaneously with blood urea nitrogen measurement. Howe ver, because M changes at the inception of dialysis, it more significant th an PCR in the evaluation of unstable patients.