title: Loss of cortisol circadian rhythm in patients with traumatic brain injury: a microdialysis evaluation.
abstract: BACKGROUND
  Traumatic brain injury (TBI) is commonly associated with disturbances of the hypothalamic-pituitary-adrenal axis secretion. Cerebral microdialysis techniques have been recently applied to measure brain interstitial cortisol levels.
  
  
  METHODS
  We evaluated for the first time the circadian rhythm of cortisol secretion at 08:00, 16:00, and 24:00 h in the acute phase of TBI by determination of total serum and brain interstitial cortisol levels (microdialysis samples) in 10 patients with TBI. Non-parametric Friedman's two way analysis of variance test was used.
  
  
  RESULTS
  Mean age was 29.8 ± 13.6 years. Median Glasgow Coma Scale score after resuscitation was 5 (range 3-10). No differences were found in total serum (P = 0.26) and brain interstitial cortisol (P = 0.77) in the whole sample. Intraindividual analysis showed that circadian variability was lost in all patients, both in serum and brain interstitial cortisol samples in the acute phase after TBI.
  
  
  CONCLUSIONS
  In our series, circadian variability of cortisol evaluated by serum and cerebral microdialysis samples seems to be lost in TBI patients.
authors.affiliation: Servei de Medicina Intensiva, Hospital Universitari Son Dureta, Andrea Doria 55, 07014, Palma de Mallorca, Illes Balears, Spain. juanantonio.llompart@ssib.es
authors.forename: Juan Antonio
authors.initials: JA
authors.lastname: Llompart-Pou
authors.forename: Gerardo
authors.initials: G
authors.lastname: Pérez
authors.forename: Joan María
authors.initials: JM
authors.lastname: Raurich
authors.forename: María
authors.initials: M
authors.lastname: Riesco
authors.forename: Marta
authors.initials: M
authors.lastname: Brell
authors.forename: Javier
authors.initials: J
authors.lastname: Ibáñez
authors.forename: Jon
authors.initials: J
authors.lastname: Pérez-Bárcena
authors.forename: Josep María
authors.initials: JM
authors.lastname: Abadal
authors.forename: Javier
authors.initials: J
authors.lastname: Homar
authors.forename: Bartolomé
authors.initials: B
authors.lastname: Burguera
mesh_terms: D000293:Adolescent; D000324:Adrenocorticotropic Hormone / Q000097:blood; D000328:Adult; D000368:Aged; D001921:Brain / Q000378:metabolism; D001930:Brain Injuries / Q000097:blood* / Q000150:complications; D002940:Circadian Rhythm / Q000502:physiology*; D015600:Glasgow Coma Scale; D006706:Homeostasis / Q000502:physiology; D006801:Humans; D006854:Hydrocortisone / Q000097:blood / Q000378:metabolism*; D007427:Intracranial Pressure / Q000502:physiology; D017551:Microdialysis / Q000379:methods; D008875:Middle Aged; D008991:Monitoring, Physiologic
chemical_list: D000324:Adrenocorticotropic Hormone; D006854:Hydrocortisone