Role of Copeptin in Predicting Postoperative Hyponatremia and Hypernatremia in Patients Undergoing Endoscopic...

Arginine vasopressin (AVP) is an important hormone responsible for maintaining sodium homeostasis after pituitary surgery. The measurement of AVP levels is difficult because of its short half-life (t 1/2 ). Copeptin is a preprohormone of AVP, and it is a more stable peptide, which can be used as surrogate marker for AVP. This study aims to assess the role of copeptin as a predictor of postoperative hyponatremia and hypernatremia in patients undergoing endoscopic pituitary adenoma surgery.

This prospective study included 50 patients who underwent endoscopic pituitary adenoma surgery. Serum copeptin levels of these patients were assessed (1) preoperatively (C1), (2) at extubation (C2), and (3) postoperative day 4 (C3). Perioperative data regarding fluid and sodium balance were collected from patients. Statistical analysis was done using the above data.

The copeptin values were assessed against the sodium disturbances. 100% of patients who developed transient diabetes insipidus had a relative decrease in C2 from C1 ( P - .0002). 88% of patients who developed early hyponatremia had a relative increase in C2 as compared with C1 ( P < .01). 75% of patients who developed delayed hyponatremia had a relative increase in C3 as compared with C1 ( P = .003).

A relative increase or decrease in early change in copeptin (C2-C1) can predict development of early hyponatremia or transient central diabetes insipidus, respectively. A relative increase in delayed change in copeptin (C3-C1) can predict development of delayed hyponatremia.