At 90 min, a stimulated copeptin of > 6.0 pmol/l provided a specificity of 97% (95% CI [0.92-1.00]) for diagnosing primary polydipsia and a stimulated copeptin of ≤ 3.0 pmol/l provided a specificity of 95% (95% CI [0.88-1.00]) for diagnosing AVP deficiency. This evidence concerns the gene AVP and neurohypophyseal diabetes insipidus.