Radioimmunoassayable plasma vasopressin associated with surgery.

Plasma vasopressin concentration was measured by radioimmunoassay before, during, and after anesthesia and surgery in ten subjects. During the short period between the onset of anesthesia and the start of operation, small elevations of vasopressin level were noted. Surgery itself was associated with significant elevations of up to 82 pg/ml. Highest levels of vasopressin were noted with major intra-abdominal surgery and lowest levels with limb surgery. The immediate postoperative period was marked by plasma vasopressin levels that were often higher than during surgery itself. Levels gradually fell to their preoperative state after three to four days. The elevated levels of vasopressin can be associated with oliguria and excessive water retention. Among the possible mechanisms for the stimulus to vasopressin secretion are pain, stress, positive pressure respiration and anoxia. This study confirms by radioimmunoassay the changes in plasma vasopressin level with surgery that have been previously described by bioassay.