At 60 min, a stimulated copeptin of ≤ 3.0 pmol/l provided a sensitivity of 71% (95% CI [0.55–0.84]) and specificity of 95% (95% CI [0.88-1.00]) for diagnosing AVP deficiency, falsely diagnosing 5% (n = 3/58) of patients with primary polydipsia and correctly diagnosing 71% (n = 27/38) patients with AVP deficiency. This evidence concerns the gene AVP and neurohypophyseal diabetes insipidus.