RESUMO
OBJECTIVE: Copeptin is a surrogate marker of arginine vasopressin release with better stability and simplicity of measurement. Postoperative copeptin levels may guide clinicians in stratifying patients who need close monitoring of fluid balance. The objective is to determine whether copeptin is a predictive marker of postoperative diabetes insipidus (DI). METHODS: This is a prospective diagnostic study. Patients who underwent neurosurgical intervention of the sellar-suprasellar regions were recruited. Serum copeptin levels were measured before and after surgery, within 24 hours. Logistic regression analysis and diagnostic performance measures were calculated to determine the relationship between postoperative copeptin levels and DI. RESULTS: Of 82 patients, 26 (31.7%) developed postoperative DI, with 7 patients (8.5%) having permanent DI. The samples for copeptin measurement were taken at 13 ± 2.1 hours postoperatively. From the receiver operating characteristic analysis, low postoperative copeptin levels (<2.5 pmol/L) demonstrated an acceptable ability to predict DI (area under the curve, 0.72; 95% CI, 0.60-0.84). Discriminative power was stronger in the permanent DI group (area under the curve, 0.82; 95% CI, 0.64-1.00). Postoperative copeptin levels <2.5 pmol/L were associated with DI (specificity > 91%). However, postoperative copeptin levels >20 pmol/L were rarely associated with DI, with a negative predictive value of 100%. CONCLUSIONS: In patients undergoing sellar-suprasellar interventions, low postoperative copeptin levels within the first postoperative day predict postoperative DI, whereas high levels exclude it. Copeptin measurement should be applied in the clinical practice of postoperative care in patients following hypothalamic-pituitary surgery. This study may expand the potential use of copeptin, including in the Asian population.