While it lacks a single optimal copeptin cut-off, the head-to-head comparison in 2023 demonstrated that the threshold values of ≤ 3.0 pmol/L exhibit > 90% specificity for identifying AVP deficiency and > 5.2 pmol/L > 90% specificity for primary polydipsia. This evidence concerns the gene AVP and hyperinsulinemic hypoglycemia, familial, 4.