Vasopressin and fluid retention after liver resection: Comparison with the renin-angiotensin-aldosterone system by...

Early postoperative edema and ascites after liver resection are common; however, the endocrine drivers of water retention are not fully defined. Arginine vasopressin (AVP) promotes antidiuresis via V2-mediated aquaporin trafficking, whereas the renin-angiotensin-aldosterone system primarily modulates sodium handling. Differences in postoperative trajectories and their relationship to early fluid retention have not been clarified in patients undergoing liver resection.

To examine postoperative changes in plasma AVP and plasma aldosterone concentration (PAC) after liver resection, and association with fluid retention.

We conducted a prospective cohort study of adults undergoing elective liver resection at a tertiary center. Blood samples were collected preoperatively, immediately post-resection, and on postoperative days (POD) 1, 2, 3, and 5. The primary objective was characterizing postoperative dynamics of AVP and PAC. Secondary objectives evaluated their temporal alignment with early fluid retention (body weight, urine output during POD 1-3) and compared hormonal profiles between major and minor resections. Analyses used trajectory and time-based comparisons by resection extent.

AVP increased sharply immediately after resection and remained above the preoperative baseline through POD 3, showing the most pronounced and sustained elevation after major liver resection. In contrast, PAC showed a transient postoperative increase that returned to near-baseline levels by POD 2. The period of elevated AVP closely matched the time frame during which early postoperative fluid retention was most evident, as indicated by greater short-term weight gain and reduced urine output. These patterns were consistent across sensitivity analyses and showed similar directional trends in subgroup comparisons based on resection extent.

AVP remains elevated longer than aldosterone and coincides with early fluid retention, particularly after major resection. Vasopressin-driven antidiuresis may be important in postoperative water retention.