Plasma levels of atrial natriuretic peptide in patients with liver cirrhosis and its relation to ascites and renal function.

Plasma immunoreactive alpha-human atrial natriuretic polypeptide (Ir-alpha-hANP) was measured by radioimmunoassay in 21 cirrhotics and 10 normal subjects. Average of Ir-alpha-hANP level in cirrhotics was significantly higher than in normal subjects (125.8 +/- 79.6 versus 28.7 +/- 12.2 pg/ml, P less than 0.001). In cirrhotics without ascites, Ir-alpha-hANP levels were positively correlated with creatinine clearance (Ccr) and urinary sodium excretion, suggesting that alpha-hANP was closely related to renal circulation and sodium homeostasis. On the contrary, in cirrhotics with ascites Ir-alpha-hANP levels were negatively correlated with Ccr. Urinary sodium excretion in cirrhotics with ascites and Ccr more than 50 ml/min was positively correlated with Ir-alpha-hANP levels. However, cirrhotics with ascites and Ccr less than 50 ml/min excreted little sodium in spite of high Ir-alpha-hANP levels. On the basis of the Ir-alpha-hANP before and after treatment of ascites, cirrhotics with ascites were subdivided into 2 groups. In group I Ir-alpha-hANP decreased from high values and in group II it was further elevated from slightly high values by treatment. The difference in renal function and plasma volume may account for the difference in Ir-alpha-hANP changes in the 2 groups.