Early Copeptin Determination Allows Prompt Diagnosis of Post-Neurosurgical Central Diabetes Insipidus

Introduction: Central diabetes insipidus (CDI) is a frequent complication of pituitary surgery, but its diagnosis lacks standardized criteria. Copeptin, a surrogate marker of arginine vasopressin release, is triggered by psycho-physical stresses such as pituitary surgery. Low postoperative copeptin could predict CDI onset. The aims of this study were the validation of copeptin as a predictor of post-neurosurgical CDI and the identification of the optimal timing for its determination. Methods: Sixty-six consecutive patients operated for a hypothalamic-pituitary lesion were evaluated. Copeptin was determined preoperatively and at 1, 6, 12, 24 and 48 h post-extubation. Fifty-eight patients were reassessed after 3-6 months post-surgery to confirm transient (3 cases) or permanent CDI (5 cases) diagnosis. Results: A marked copeptin peak was identified at 1 h after extubation, when a value below or equal to 12.8 pmol/L had a good accuracy in identifying CDI cases (AUC 0.866, 95% CI 0.751-0.941). Moreover, a copeptin peak above 4.2 pmol/L excluded permanent forms (AUC 1, 95% CI 0.629-1). Regression analysis identified copeptin as the only significant predictor of CDI (OR 0.86, 95% CI 0.75-0.98, p = 0.02). A copeptin T1/T0 ratio below or equal to 1.47 identified patients at risk of isolated biochemical alterations even in the absence of an overt CDI. Conclusions: A prompt increase of copeptin is expected at 1 h after extubation. The absence of this peak is a reliable predictor of post-neurosurgical CDI.