In patients undergoing pituitary surgery, copeptin levels represent a novel marker for postoperative diabetes insipidus, according to data published in the Journal of Clinical Endocrinology & Metabolism.
“Central diabetes insipidus is observed in 16% to 34% of patients recovering from sellar region operations. Although generally transient, this condition may prolong hospitalization and cause morbidity after pituitary procedures, and may lead to severe hypernatremia if fluid is not immediately replenished,” the researchers wrote.
“Therefore monitoring for [diabetes insipidus] is mandatory during the first postoperative days, and timely, accurate diagnosis followed by correct treatment is crucial.”
For their study, the researchers sought to assess the accuracy of copeptin levels and kinetics after pituitary surgery to predict postoperative diabetes insipidus after sellar region procedures. To do so, they conducted a prospective observational cohort study at two referral centers in Switzerland and one in Canada in which they measured daily postoperative copeptin levels until discharge.
A total of 205 patients undergoing pituitary surgery were included in the study — 50 (24.4%) of whom developed postoperative diabetes insipidus. Results revealed significantly lower median copeptin levels in patients who developed diabetes insipidus, as compared with those who did not (2.9 pmol/L vs. 10.8 pmol/L; P<.001).
A strong link between postoperative copeptin concentrations and diabetes insipidus was also observed in logistic regression analysis, even after accounting for factors that predispose patients to the condition (adjusted OR=1.41; 95% CI, 1.16-1.73), according to the data.
Further, 22 of 27 patients with diabetes insipidus had copeptin levels lower than 2.5 pmol/L, yielding a positive predictive value of 81% and a specificity of 97%. In contrast, only one patient of 40 with copeptin levels greater than 30 pmol/L had diabetes insipidus on day 1 after surgery (negative predictive value, 95%; sensitivity, 94%).
The study is limited by the fact that there is a lack of standardized diagnostic criteria for diabetes insipidus and the fact that blood samples to measure copeptin levels were collected during everyday care as opposed to at fixed time points, the researchers noted.
Ultimately, however, they concluded that the findings identify copeptin as “a new, early, and reliable single marker for postoperative [diabetes insipidus]” after pituitary surgery.
“Postoperative copeptin measurements appear to provide important information for risk stratification and may identify patients benefitting from closer inpatient observation and patients in whom safe hospital discharge is possible,” the researchers wrote.