title: A comparison of capillary, venous, and salivary cortisol sampling after intense exercise.
abstract: Venipuncture is expensive, invasive, and impractical for many sport-science and clinical-based settings. Salivary free cortisol is often cited as a noninvasive practical alternative. However, when cortisol concentrations exceed the corticosteroid-binding globulin (CBG) point of 500 nmol/L, a lack of agreement between salivary and venous blood cortisol has been found. Alternatively, capillary blood may present a minimally invasive, cost-effective, and practical surrogate for determining cortisol concentration.
  
  
  OBJECTIVE
  The aim of this study was to determine whether cortisol concentrations sampled from capillary blood and saliva accurately reflect those found in venous blood across a large range of concentrations after intense exercise.
  
  
  METHODS
  Eleven healthy aerobically trained male subjects were recruited. Capillary, salivary, and venous blood samples were collected before and after (immediately and 5, 10, 15, and 20 min after) a treadmill VO(2) max test.
  
  
  RESULTS
  Capillary and venous concentrations increased at a similar rate after exercise (Cohen d.14-.33), increasing up to 15 min postexercise before a decline was seen. Salivary cortisol values increased at a slower rate than venous and capillary cortisol but continued to increase 15 min postexercise (Cohen d .19-.47 and .09-.72, respectively).
  
  
  CONCLUSIONS
  Capillary cortisol accurately reflects concentrations assayed from venous blood across a range of values below and above the CBG binding point. Capillary sampling provides a minimally invasive, cost-effective, practical surrogate for assessment of hypothalamic-pituitary-gland function.
authors.affiliation: School of Sport and Exercise, University of Gloucestershire, Gloucester, UK.
authors.forename: Simon M
authors.initials: SM
authors.lastname: Fryer
authors.forename: Tabitha
authors.initials: T
authors.lastname: Dickson
authors.forename: Stephen
authors.initials: S
authors.lastname: Hillier
authors.forename: Lee
authors.initials: L
authors.lastname: Stoner
authors.forename: Carl
authors.initials: C
authors.lastname: Scarrott
authors.forename: Nick
authors.initials: N
authors.lastname: Draper
mesh_terms: D000328:Adult; D002196:Capillaries; D004797:Enzyme-Linked Immunosorbent Assay; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D006801:Humans; D006854:Hydrocortisone / Q000032:analysis* / Q000097:blood; D008297:Male; D027544:Salvia / Q000737:chemistry*; D014680:Veins; D055815:Young Adult
chemical_list: D006854:Hydrocortisone