Table 2.

Overview copeptin cut-offs

Test/Indication	Time point measurement	Copeptin cut-off	Test performance	Reference
Random copeptin measurement	Any time	>21.4 pmol/L = nephrogenic diabetes insipidus	Diagnostic accuracy 100%	Timper K, et al. J Clin Endocrinol Metab 2015 (41)
Hypertonic saline infusion test	Once plasma sodium ≥147 mmol/L	≤4.9 pmol/L = central diabetes insipidus	Diagnostic accuracy 97%	Fenske W, et al. N Engl J Med 2018 (43)
		>4.9 pmol/L = primary polydipsia		Timper K, et al. J Clin Endocrinol Metab 2015 (41)
Arginine infusion test	60 minutes after start of arginine infusion	≤3.8 pmol/L = central diabetes insipidus	Diagnostic accuracy 93%	Winzeler B, et al. Lancet 2019 (44)
		>3.8 pmol/L = primary polydipsia
Pituitary surgery stimulated copeptin	1st postoperative day	<2.5 pmol/L = central diabetes insipidus	Positive predictive value 81%, specificity 97%	Winzeler B, et al. J Clin Endocrinol Metab 2015 (48)
		>30 pmol/L = no central diabetes insipidus	Negative predictive value 95%, sensitivity 94%
Hypernatremia in hospitalized patients	Plasma sodium >155 mmol/L	≤4.4 pmol/L = central diabetes insipidus	Sensitivity 100%, specificity 99%	Nigro N, et al. Crit Care 2018 (49)
Hyponatremia in hospitalized patients	Plasma sodium <125 mmol/L	>84 pmol/L = hypovolemic hyponatremia	Sensitivity 23%, specificity 90%	Nigro N, et al. Clin Endocrinol 2017 (50)
		<3.9 pmol/L = primary polydipsia	Sensitivity 58%, specificity 91%