Plasma Concentration of Uroguanylin in Patients on Maintenance Dialysis Therapy

BACKGROUND: Uroguanylin, originally isolated from urine, is a new natriuretic peptide. Its plasma level is increased in association with renal impairment and fluid retention in patients with renal diseases. METHODS: Uroguanylin concentrations were measured in patients on hemodialysis (HD, n = 76) and those on continuous ambulatory peritoneal dialysis (CAPD, n = 10) using a sensitive ra- dioimmunoassay for human uroguanylin. RESULTS: Plasma concentrations of immunoreactive (ir)-uroguanylin in the patients on HD and CAPD (212.0 +/- 17.4 and 245.3 +/- 39.5 fmol/ml) were significantly higher than the value for the normal controls (5.0 +/- 0.3 fmol/ml). Plasma ir-uroguanylin levels before the start of regular HD were correlated with predialysis excess weight based on their dry weights (r = 0.33, p < 0.01) and with dialysis duration (r = 0.26, p < 0.05). The plasma levels in patients with HD, for whom high-flux membranes were used, were decreased at the end of regular HD as compared with the prior levels (p < 0.05), but not in those who underwent HD with conventional membranes. CONCLUSION: These findings suggest that the plasma ir-uroguanylin level is related to the patient's volume status as well as renal impairment. Whether the accumulation of uroguanylin has a pathological effect has yet to be determined.