Copeptin as a Diagnostic Marker in the Management of Neurosurgical Patients with Disturbance of Water Homeostasis

Introduction: Disorders of water balance caused by disturbances in arginine vasopressin (AVP) secretion remain a common cause of morbidity after pituitary surgery. Levels of AVP might contribute to a straightforward diagnosis, although, its measurement is cumbersome. Copeptin, the stable C-terminal glycopeptide of the AVP prohormone, is a reliable surrogate of plasma AVP. Our aim is to elucidate whether Copeptin may become a useful marker in the diagnostic approach of water and electrolyte disturbances after pituitary surgery. Material and Methods: From the preoperative day to the day of discharge, patients undergoing transsphenoidal or transcranial pituitary surgery were daily monitored for clinical items (i.e., vital signs, balance of fluids), routine laboratory parameters, and copeptin. Results: We present preliminary results of 12 patients (mean age, 53 years; 58.3% females) with hormone-inactive (4) and hormone-secreting (3) pituitary adenomas, meningiomas (2), and Rathke’s cleft cysts (3). Nine patients showed a normal postoperative course, and diabetes insipidus (DI) occurred in three patients within 36 hours after surgery. In patients with an uneventful postoperative course, surgery induced a significant copeptin release ( P = 0.008), with an increase from 4.2 pM (±2.3) preoperatively to 12.2 pM (±9.2) postoperatively (measured within 24 hours after surgery). Copeptin levels in patients with postoperative DI decreased in all three patients from 3.85 pM (±0.85) preoperatively to 2.33 pM (±0.35) after surgery. The mean difference in copeptin levels from pre- to postoperatively in patients with uneventful course was +4.1 versus −1.76 in patients with DI ( P = 0.009). Conclusion: Copeptin may become a novel tool in the early goal-directed management of patients with disturbance of the neuroendocrine homeostasis after pituitary surgery.