Setting analytical performance specifications for copeptin-based testing.

This document discusses the use of copeptin-based testing as a diagnostic tool for differentiating between arginine vasopressin (AVP) deficiency and primary polydipsia in individuals with polyuria-polydipsia syndrome. The document presents the results of international trials that found specific copeptin concentrations associated with a diagnosis of AVP deficiency or primary polydipsia in adults and children. The document also explores the derivation of analytical performance specifications (APS) for copeptin, based on clinical requirements and biological variation estimates. The APS derived from different models can inform laboratory practice, such as analytical standardization and quality control procedures. [Extracted from the article]