Copeptin
| Copeptin | ||
|---|---|---|
| Properties of human protein | ||
| Mass / length primary structure | 39 amino acids | |
| Precursor | AVP-NPII | |
| Identifier | ||
| Gene name | AVP | |
| External IDs | ||
Copeptin (also C-terminal proAVP , CT-proAVP ) is a 39 amino acid glycosylated peptide that is synthesized as a prohormone in the hypothalamus (preprovasopressin) together with vasopressin (also known as AVP or antidiuretic hormone ) and neurophysin II . The gradual proteolytic cleavage of the prohormone results in the release of the peptides vasopressin, neurophysin II and copeptin in equimolar amounts. Copeptin is produced by splitting off the C-terminal part of the prohormone.
The physiological significance of copeptin is not yet fully understood. Participation in the folding and transport of maturing vasopressin from the hypothalamus to the neurohypophysis is discussed . After a corresponding stimulus (osmotic stimulus or stress reaction), copeptin is released from the neurohypophysis into the bloodstream together with vasopressin and neurophysin II.
Copeptin values are particularly important in patients with severe illnesses such as sepsis , but e.g. B. also in heart failure increased.
Unlike AVP, copeptin is stable in serum and EDTA plasma for 7 days at room temperature.
Diagnosis
Due to its biosynthesis and its properties, copeptin is used as an alternative biomarker for AVP determination for the diagnosis of various diseases.
One advantage of copeptin for diagnostics is the relative stability of the analyte. In contrast to copeptin, the hormonally active vasopressin is a small (9 amino acids) and very unstable molecule. In order to ensure a valid measurement of vasopressin, it is recommended to take the blood sample with pre-cooled tubes (only EDTA plasma), to transport the sample cooled and to store it at −20 ° C. The processing of blood samples in which the vasopressin content is to be determined is also time-consuming and technically demanding. This has limited the use of vasopressin measurements in routine clinical practice, although often indicated and useful to the patient. Copeptin, on the other hand, is stable in both blood and plasma and is therefore easy to measure. Since copeptin and vasopressin are split off from the prohormone in equal proportions , copeptin is considered a surrogate marker for vasopressin, which is more difficult to determine. Due to its technical advantages, the determination of copeptin has already found its way into the routine in various indications.
For example, a combination of copeptin and troponin can improve the early diagnosis of myocardial infarction . Further research is focused on the role of copeptin in stroke . A connection between copeptin values and the prognosis and mortality of the disease is seen here. Copeptin can also be used as a biomarker for risks of pneumonia or for the differential diagnosis in central diabetes insipidus or polyuria-polydipsia syndrome.
Individual evidence
- ↑ NG Morgenthaler, J. Struck, C. Alonso, A. Bergmann: Assay for the measurement of copeptin, a stable peptide derived from the precursor of vasopressin. In: Trends Endocrinol Metab. Volume 19, No. 2, March 2008, pp. 43-49.
- ^ Khan in: Circulation . Volume 115, No. 16, April 24, 2007, pp. 2103-2110. PMID 18291667 .
- ↑ http://www.cardiosource.com/cvn/index.asp?videoid=990 ( page no longer available , search in web archives ) Info: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice.
- ↑ T. Reichlin et al.: Incremental value of copeptin for rapid rule out of acute myocardial infarction. In: J Am Coll Cardiol . Volume 54, No. 1, June 30, 2009, pp. 60-68. PMID 19555842 .
- ↑ Katan et al. In: Ann Neurol. Volume 66, No. 6, December 2009, pp. 799-808. PMID 20035506 .
- ↑ M. Kolditz et al: Copeptin and MR-proADM as biomarkers. In: Respir. Medicine. Volume 106, 2012, pp. 1320-1328.
- ^ W. Fenske, M. Christ-Crain: The role of CT-proAVP (copeptin) in the clarification of the polyuria-polydipsia syndrome. In: Med. World. Volume 1, 2011, pp. 3-8.
- ↑ W. Fenske, M. Quinkler, D. Lorenz, K. plait, U. Haagen, M. Papassotiriou, AH Pfeiffer, M. Fassnacht, p spoilers, as Allolio: copeptin in the differential diagnosis of polyuria-polydipsia syndrome : revisiting the direct and indirect water deprivation test. In: The Journal of Clinical Endocrinology and Metabolism. 2011, pp. 2010–2345.
