Urotensin II Levels Are an Important Marker for the Severity of Portal Hypertension in Children

Background and Aim: Urotensin II (U-II), a somatostatin-like cyclic peptide, was recently identified as the most potent human vasoconstrictor peptide; however, the contribution of U-II-mediated alterations in peripheral vascular tone in disease states such as chronic liver disease and portal hypertension is poorly characterised. There are no data examining U-II in chronic liver disease in children. In this study, we aimed to determine whether U-II levels in healthy children are ontogenically regulated and we explored the effect of chronic liver disease on peripheral circulating U-II levels. Materials and Methods: U-II levels from healthy controls (n = 129) were compared with a healthy adult population (n = 80) in addition to a well-characterised cohort of children with chronic liver disease (n = 20). U-II was measured by radioimmunoassay. Results: There was no correlation between U-II and age in healthy children (r(2) - 0, P - 0.8). U-II levels were similar between the paediatric and the adult control populations (1.35 + 0.96 vs 1.25 + 0.78, P = 0.8). U-II was significantly elevated in children with liver disease compared with controls (1.35 +/- 0.96 pmol/L vs 3.56 +/- 2.21 pmol/L; P < 0.001). In addition, U-II levels positively correlated with severity of liver disease as determined by Child-Pugh score (P < 0.05) and paediatric end-stage liver disease score (P < 0.001). Levels of U-II also correlated with long-term clinical outcome. Conclusions: These data suggest that U-II is an important marker of severity of portal hypertension in children. It is independent of age and may be a potential therapeutic target in the chronic liver disease population.