The cut-off level of copeptin was 4.4 pmol/L, whereas in ambulatory patients with central diabetes insipidus and patients with post-surgical central diabetes insipidus copeptin levels < 2.6 pmol/L and < 2.9 pmol/L, respectively, diagnosed diabetes insipidus [29, 30]. The gene discussed is AVP; the disease is diabetes insipidus.