Copeptin and the syndrome of inappropriate antidiuresis (SIAD) after pituitary transsphenoidal surgery

Objective: This study evaluates the predictive value of copeptin for syndrome of inappropriate antidiuresis (SIAD) postpituitary transsphenoidal surgery (TSS). Design: Data from 133 consecutive patients undergoing TSS (November 2017–October 2022) at Oxford University Hospitals NHS trust are presented in this retrospective study. Methods: Logistic regression (LR) and receiver operating characteristic (ROC) curves were performed to evaluate the diagnostic utility of copeptin. The Mann–Whitney U test was used to compare copeptin levels between the SIAD and no SIAD groups. Results: Fourteen patients (10.8%) developed SIAD. Copeptin was available in 121, 53 and 87 patients for Days 1, 241 and 8 post-TSS, respectively. LR for Day 1 copeptin to predict SIAD gave an odds ratio (OR) of 1.0 (95%CI 42 0.84–1.20, p =.99), area under-ROC curve (AUC) was 0.49; Day 2 copeptin OR was 0.65 (95%CI 0.39–1.19, 43 p =.77), AUC was 0.57 LR for Day 1 sodium to predict SIAD gave an odds ratio (OR) of 1.0 (95%CI 0.85–1.21, p =.99), AUC was 0.50. Conclusions: In conclusion, our data provide no evidence for copeptin as a predictive marker for post-TSS SIAD.