title: Day-to-day variations in salivary cortisol measurements.
abstract: OBJECTIVE
  The purpose of this study was to clarify the day-to-day variations of salivary cortisol to discuss the appropriate timing for collecting saliva in a day for stress evaluation.
  
  
  METHODS
  Saliva samples from twelve healthy adults were collected by means of Salivette(®) (SARSTEDT Co.) three times per day, immediately after awakening (Time1), 6:00 PM (Time2) and 30 min before going to bed (Time3), on 5 nonconsecutive days. Cortisol concentration was measured using a radioimmunoassay.
  
  
  RESULTS
  Salivary cortisol concentration showed the larger value at Time1 than that at Time2. The mean value of %CV for day-to-day variation showed the smallest value at Time1 (mean: 43.1%) and the largest value at Time3 (mean: 100.3%). There were significant differences in %CV value between Time1 and Time3, Time2 (mean: 64.1%) and Time3.
  
  
  CONCLUSIONS
  There are considerable day-to-day variations in salivary cortisol concentration measurements. From the viewpoint of day-to-day variation, collecting saliva immediately after awakening in the morning is thought to be more advantageous for evaluating cortisol concentration.
authors.affiliation: Department of Gnatho-occlusal Function, Graduate School of Dental Medicine, Hokkaido University, Kita 13, Nishi 7, Kita-ku, Sapporo 060-8586, Japan. shinpei@den.hokudai.ac.jp
authors.forename: Shimpei
authors.initials: S
authors.lastname: Matsuda
authors.forename: Taihiko
authors.initials: T
authors.lastname: Yamaguchi
authors.forename: Kazuki
authors.initials: K
authors.lastname: Okada
authors.forename: Akihito
authors.initials: A
authors.lastname: Gotouda
authors.forename: Saki
authors.initials: S
authors.lastname: Mikami
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000032:analysis; D002940:Circadian Rhythm / Q000502:physiology*; D005260:Female; D006801:Humans; D006854:Hydrocortisone / Q000032:analysis*; D007030:Hypothalamo-Hypophyseal System / Q000502:physiology; D008297:Male; D010913:Pituitary-Adrenal System; D012463:Saliva / Q000737:chemistry*; D013315:Stress, Psychological / Q000175:diagnosis*; D055815:Young Adult
chemical_list: D015415:Biomarkers; D006854:Hydrocortisone