Changes in Plasma Copeptin, the C-Terminal Portion of Arginine Vasopressin during Water Deprivation and Excess in Healthy Subjects

• Published in: The journal of clinical endocrinology and metabolism Vol. 92; no. 10; pp. 3973 - 3978
• Main Authors: Szinnai, Gabor, Morgenthaler, Nils G., Berneis, Kaspar, Struck, Joachim, Müller, Beat, Keller, Ulrich, Christ-Crain, Mirjam
• Format: Journal Article
• Language: English
• Published: Bethesda, MD Endocrine Society 01.10.2007; Copyright by The Endocrine Society
• Subjects: Adult; Arginine Vasopressin - blood; Arginine Vasopressin - chemistry; Biological and medical sciences; Biomarkers - blood; Blood Volume - physiology; Chemistry, Clinical - methods; Chemistry, Clinical - standards; Drinking - physiology; Endocrinopathies; Feeding. Feeding behavior; Female; Fundamental and applied biological sciences. Psychology; Glycopeptides - blood; Humans; Hypovolemia - blood; Male; Medical sciences; Osmolar Concentration; Protein Structure, Tertiary; Reproducibility of Results; Sodium - blood; Vertebrates: anatomy and physiology, studies on body, several organs or systems; Vertebrates: endocrinology; Water Deprivation - physiology; Water; Biological fluid; Obesity; Deprivation; Poverty; Healthy subject; Nutrition; 8-Arginine vasopressin; Nutrition disorder; Metabolic diseases; Change; Blood plasma; C terminal-Sequence; Endocrinology; Nutritional status
• ISSN: 0021-972X; 1945-7197
• DOI: 10.1210/jc.2007-0232

Context: The measurement of arginine vasopressin (AVP) is often cumbersome because it is unstable with a short half-life time. AVP is derived from a larger precursor peptide along with the more stable peptide copeptin. Copeptin is the C-terminal part of provasopressin and has been shown to be a useful tool to indicate AVP concentration in critically ill patients. Objective: The objective of the study was to evaluate the clinical usefulness of copeptin as a new marker in disordered states of blood volume and plasma osmolality. Design and Setting: This was a prospective observational study in a university hospital. Participants and Main Outcome Measures: Three techniques with respective control studies were used in 24 healthy adults to produce changes in plasma osmolality and/or volume: 1) a 28-h water deprivation, 2) a 17-h hypertonic saline infusion combined with thirsting, and 3) a hypotonic saline infusion with iv desmopressin administration during free water intake. Results: Water deprivation produced a weight loss of 1.7 kg, an increase in plasma osmolality to 294.8 ± 4.3 mosmol/kg, and an increase of copeptin from 4.6 ± 1.7 pmol/liter to 9.2 ± 5.2 pmol/liter (P < 0.0001). During hypertonic saline infusion and thirsting with a raise of plasma osmolality to 296.1 ± 3.4 mosmol/kg, copeptin increased from 4.9 ± 3.0 pmol/liter to 19.9 ± 4.8 pmol/liter (P < 0.0001). Conversely, during hypotonic saline infusion, plasma osmolality decreased to 271.3 ± 4.1 mosmol/kg, and copeptin decreased from 6.2 ± 2.4 pmol/liter to 2.4 ± 2.1 pmol/liter (P < 0.01). Conclusion: Copeptin shows identical changes during disordered water states as previously shown for AVP. It might be a reliable marker of AVP secretion and substitute for the measurement of circulating AVP levels in clinical routine.