[Copeptin is a new diagnostic biomarker for diabetes insipidus].

Differential diagnosis of diabetes insipidus is challenging. The water deprivation test is the current gold standard, but the test is cumbersome, and the diagnostic performance is poor. Copeptin, which is a split product of the vasopressin pre-propeptide, appears to be a robust biomarker in the circulation and a promising tool for the diagnosis of patients with polyuria and polydipsia, especially when measured in conjunction with intravenous infusion of arginine, as summarised in this review.