copeptin

Copeptin (also known as CT-proAVP) is a 39-amino acid-long peptide derived from the C-terminus of pre-pro-hormone of arginine vasopressin, and copeptin. Arginine vasopressin (AVP), also known as the antidiuretic hormone (ADH), is encoded by the AVP gene and is involved in multiple cardiovascular and renal pathways and abnormal level of AVP are associated with various diseases. Hence measurement of AVP would be useful, but is not commonly carried out in clinical practice because of its very short half-life making it difficult to quantify. In contrast, copeptin can be immunologically tested with ease and therefore can be used as a vasopressin surrogate marker.

== Synthesis and secretion == Copeptin is a 39-amino acid-long, glycosylated peptide. It is synthesized mainly in the paraventricular neurons of the hypothalamus and in the supraoptic nucleus. During axonal transport, pre-pro-AVP is proteolytically cleaved into vasopressin, and copeptin. These molecules are then stored in secretory granules in the posterior pituitary and released upon osmotic or non-osmotic (hemodynamical; stress-related) stimuli.