title: Changes in copeptin and bioactive vasopressin in runners with and without hyponatremia.
abstract: OBJECTIVE
  To evaluate changes in both the N-terminal (arginine vasopressin; AVP) and C-terminal (copeptin) fragments of the vasopressin prohormone before, during, and after an ultramarathon race and to assess vasopressin and copeptin concentrations in runners with and without hyponatremia.
  
  
  METHODS
  Observational study.
  
  
  METHODS
  Three trials (2 sodium balance and 1 hyponatremia treatment) in 2 separate approximately 160-km footraces [Western States Endurance Run (WSER) and Javelina Jundred (JJ100)].
  
  
  METHODS
  Six hyponatremic and 20 normonatremic runners; 19 finishers with 7 completing 100 km.
  
  
  METHODS
  Plasma AVP ([AVP]p), copeptin ([copeptin]p), sodium ([Na]p), and protein (%plasma volume change; %PV) concentrations.
  
  
  RESULTS
  In the WSER Sodium Trial, a 3-fold prerace to postrace increase in both [AVP]p (0.7 ± 0.4 to 2.7 ± 1.9 pg/mL; P < 0.05) and [copeptin]p (10.3 ± 12.5 to 28.2 ± 16.3 pmol/L; nonsignificant) occurred, despite a 2 mEq/L decrease in [Na]p (138.7 ± 2.3 to 136.7 ± 1.6 mEq/L; NS). A significant correlation was noted between [AVP]p and [copeptin]p postrace (r = 0.82; P < 0.05). In the WSER Treatment Trial, despite the presence of hyponatremia pretreatment versus posttreatment ([Na]p = 130.3 vs 133.5 mEq/L, respectively), both [AVP]p (3.2 vs 2.1 pg/mL) and [copeptin]p (22.5 vs 24.9 pmol/L) were well above the detectable levels. A significant correlation was noted between [AVP]p and [copeptin]p 60 minutes after treatment (r = 0.94; P < 0.05). In the JJ100 Sodium Trial, significant correlations were found between [copeptin]p change and %PV change (r = -0.34; P < 0.05) and between [AVP]p change and [Na]p change (r = 0.39; P < 0.05) but not vice-versa.
  
  
  CONCLUSIONS
  [Copeptin]p seems to be a reliable surrogate of stimulated [AVP]p during exercise. Nonosmotic vasopressin stimulation occurs during ultradistance running. [Copeptin]p may better reflect chronic (%PV) vasopressin secretion under conditions of endurance exercise.
authors.affiliation: Exercise Science Program, School of Health Sciences, Oakland University, Rochester, Michigan. USA. hew@oakland.edu
authors.forename: Tamara
authors.initials: T
authors.lastname: Hew-Butler
authors.forename: Martin D
authors.initials: MD
authors.lastname: Hoffman
authors.forename: Kristin J
authors.initials: KJ
authors.lastname: Stuempfle
authors.forename: Ian R
authors.initials: IR
authors.lastname: Rogers
authors.forename: Nils G
authors.initials: NG
authors.lastname: Morgenthaler
authors.forename: Joseph G
authors.initials: JG
authors.lastname: Verbalis
mesh_terms: D000328:Adult; D056352:Athletes; D001798:Blood Proteins / Q000502:physiology; D001810:Blood Volume / Q000502:physiology; D005260:Female; D006020:Glycopeptides / Q000097:blood / Q000502:physiology*; D006801:Humans; D007010:Hyponatremia / Q000097:blood / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D010807:Physical Endurance / Q000502:physiology; D012420:Running / Q000502:physiology*; D012964:Sodium / Q000097:blood / Q000502:physiology; D014667:Vasopressins / Q000097:blood / Q000502:physiology*
chemical_list: D001798:Blood Proteins; D006020:Glycopeptides; C048197:copeptins; D014667:Vasopressins; D012964:Sodium