Non-Water deprived, non-fasting adults: <16.3 pmol/L
Non-water deprived, fasting (>8hrs) adults: <15.2 pmol/L
Non-water deprived, non-fasting paediatric subjects: <14.5 pmol/L
For the investigation of diabetes insipidus (DI) and primary polydipsia (PP) in patients with confimed polyuria (>40 mL/kg/d.*
A baseline Copeptin level >21.4 pmol/L is 100% sensitive and specific for nephrogenic diabetes insipidus.
A baseline Copeptin level <2.6 pmol/L with prior fluid deprivation (>8hr) will indicate complete central DI likely
A stimulated Copeptin** >4.9 pmol/L PP likely and <4.9 pmol/L partial central DI likely (94.0% specificity and 94.4% sensitivity)
*Without concurrent diabetes mellitus, hypercalcemia, pregnancy, uncorrected thyroid or adrenal insufficieny, and heart failure; **at sodium levels >147mmol/L following water deprivation.