A post-hoc internal validation of arginine-stimulated copeptin cut-offs for diagnosing arginine vasopressin (AVP) deficiency (central diabetes insipidus)
Authors' conclusion
This analysis validates two new copeptin cut-offs of the arginine stimulation test to distinguish AVP deficiency from primary polydipsia: >5.2 pmol/L for high specificity in diagnosing primary polydipsia and ≤ 3.0 pmol/L for high specificity in diagnosing AVP deficiency. These thresholds might offer a practical initial alternative to hypertonic saline testing.
Study context
- Population
- Adults with confirmed AVP deficiency (central diabetes insipidus) or primary polydipsia; AVP deficiency n = 38, primary polydipsia n = 58May 2013–June 2018
- Participants
- 96 adults
- Comparison
- Arginine-stimulated copeptin cut-offs ≤ 3.0 pmol/L and > 5.2 pmol/L at 60 min
- Primary endpoint
- Internal validation of arginine-stimulated copeptin cut-offs > 5.2pmol/L (>90% specificity for primary polydipsia) and ≤ 3.0 pmol/L (>90% specificity for AVP deficiency)
- Follow-up
- 60 min after arginine infusion
Methodological detailsinternal validation
- Internal validation
Primary result
As reported in the abstract
Diagnostic specificity
| Group | Specificity for AVP deficiency | AVP deficiency correctly identified | Specificity for primary polydipsia | Primary polydipsia correctly identified |
|---|---|---|---|---|
| Copeptin ≤ 3.0 pmol/L | 95% (95% CI: 0.88-1.00) | 71% (n = 27/38) | ||
| Copeptin > 5.2 pmol/L | 97% (95% CI: 0.92-1.00) | 69% (n = 40/58) |
Specificity for AVP deficiency
Copeptin ≤ 3.0 pmol/L95% (95% CI: 0.88-1.00)
Copeptin > 5.2 pmol/L— not stated in the abstract
AVP deficiency correctly identified
Copeptin ≤ 3.0 pmol/L71% (n = 27/38)
Copeptin > 5.2 pmol/L— not stated in the abstract
Specificity for primary polydipsia
Copeptin ≤ 3.0 pmol/L— not stated in the abstract
Copeptin > 5.2 pmol/L97% (95% CI: 0.92-1.00)
Primary polydipsia correctly identified
Copeptin ≤ 3.0 pmol/L— not stated in the abstract
Copeptin > 5.2 pmol/L69% (n = 40/58)
Original publication
A post-hoc internal validation of arginine-stimulated copeptin cut-offs for diagnosing AVP deficiency (central diabetes insipidus). Pituitary. Published 26 April 2025. doi:10.
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