The polyuria-polydipsia syndrome includes three different conditions: central diabetes insipidus, nephrogenic diabetes insipidus and primary polydipsia. Differentiating between these entities is crucial but can been challenging in clinical practice. Recently, measurement of plasma copeptin, the C-terminal segment of the arginine vasopressin prohormone, has become routinely available and now has an important role in the differentiation of polyuria-polydipsia syndrome.
- Polyuria-polydipsia syndrome comprises central diabetes insipidus (DI), nephrogenic DI and primary polydipsia.
- The introduction of plasma copeptin measurements has advanced the investigation of polyuria-polydipsia syndrome.
- Baseline plasma copeptin measurements are useful for the diagnosis of nephrogenic DI.
- Stimulated plasma copeptin measurements are useful for the differentiation of central DI and primary polydipsia.
- The hypertonic saline-stimulated copeptin test has replaced the water deprivation test as the gold standard test for the diagnosis of central DI.