Utility of Copeptin Measurement in the Differential Diagnosis of Diabetes Insipidus

Abstract

Given the different etiologies of Diabetes Insipidus disorders, there are major differences in treatment. For example, while central diabetes insipidus is mainly treated with exogenous AVP (desmopressin), patients with primary polydipsia are advised to slowly reduce their fluid intake. Therefore, a diagnostic test with high diagnostic accuracy is crucial to avoid wrong treatment decisions. While the standard water deprivation test as described for patient has been the diagnostic gold standard for decades despite its low diagnostic accuracy of only 70%, recent evaluations showed improved diagnostic accuracy for copeptin based tests. In addition to diagnosing diabetes insipidus in the outpatient clinic, copeptin measurement has also been proposed in the evaluation of postoperative central diabetes insipidus. While 1 study showed a high diagnostic accuracy of 100% for insulin-induced hypoglycemia-stimulated copeptin with a cut-off value of 4.75 pmol/L to detect central diabetes insipidus 3 months after pituitary surgery, the risks of this test outweigh its potential value.