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Copeptin

A 39-amino acid-long peptide derived from a pre-pro-hormone consisting of vasopressin, neurophysin II and copeptin.

Also known as C-terminal pro-arginine vasopressin.

Arginine vasopressin (AVP), also known as the antidiuretic hormone (ADH), is involved in multiple cardiovascular and renal pathways and functions.

Vasopressin measurements are not commonly used because of the biochemical features of the molecule: its small size and very short half-life.

Reflects arginine vasopressin release with a 1:1 stoichiometric generation ratio.

The activation of the arginine-vasopressin system may mark the response to acute endogenous stress, as occurs in acute myocardial infarction.

Copeptin testing is used as a vasopressin surrogate.

Copeptin is a 39-amino acid-long, glycosylated peptide.

Synthesized mainly in the paraventricular neurons of the hypothalamus and in the supraoptical nucleus.

During axonal transport, pre-pro-AVP is proteolytically cleaved into vasopressin, neurophysin II and copeptin.

These molecules are stored in secretory granules in the posterior pituitary and released upon osmotic or non-osmotic stimuli.

No known biological role for copeptin.

Levels are increased during acute myocardial infarction.

When pre-pro-vasopressin is processed during the axonal transport, copeptin may contribute to the 3D folding of vasopressin.

Copeptin testing is closely linked to the pathophysiological pathways in which vasopressin is involvedĀ : polydipsia-polyuria syndrome, hyponatremia, syndrome of inappropriate antidiuretic hormone secretion (SIADH) as well as heart failure and acute coronary syndrome.

The concentration of copeptin ranges from 1 to 12 pmol/L in healthy individuals.

Levels slightly higher in men than in women.

Levels not influenced by age.

Responds to serum osmolality fluctuations comparable to those of vasopressin.

Patients with diabetes insipidus with very low levels of vasopressin also show very low levels of copeptin in blood plasma.

Patients suffering from syndrome of inappropriate antidiuretic hormone secretion show both high levels of vasopressin and copeptin.

Is released very early during the onset of an acute myocardial infarction.

It is suggested the combination of a negative result of troponin together with a negative result of copeptin can rule-out AMI at emergency department presentation with a negative predictive value ranging from 95% to 100%.

High levels in congestive heart failure , as with vasopressin, associated with a poor prognosis.

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