title: Salivary cortisol can replace free serum cortisol measurements in patients with septic shock.
abstract: BACKGROUND
  There is a renewed interest in adrenal function during severe sepsis. Most studies have used total serum cortisol levels; however, only free serum cortisol is biologically active. The aim of this study was to determine the validity of salivary cortisol levels as a surrogate for free serum cortisol levels during septic shock.
  
  
  METHODS
  Fifty-seven patients with septic shock were studied to determine the correlation between total serum cortisol and salivary cortisol to free serum cortisol levels. Thirty-eight patients were included in the salivary to free serum cortisol correlation. Salivary cortisol level was tested by enzyme immunoassay. Serum total cortisol, free cortisol, and cortisol-binding globulin (CBG) levels were determined by liquid chromatography-mass spectrometry, equilibrium analysis, and radioimmunoassay, respectively.
  
  
  RESULTS
  The mean ± SD age was 56.6 ± 18.5 years. Fifty-seven percent were women. APACHE (Acute Physiology and Chronic Health Evaluation) II score median was 26, Simplified Acute Physiology Score II median was 61, and Sequential Organ Failure Assessment median was 13. The correlation between salivary and free serum cortisol levels was 0.79 (95% CI, 0.63-0.89; P < .0001). The correlation between free serum cortisol and total serum cortisol levels was 0.86 (95% CI, 0.78-0.92; P < .0001). The mean ± SD free serum cortisol level was 2.27 ± 1.64 μg/dL. The mean ± SD salivary cortisol level was 2.60 ± 2.69 μg/dL. The mean ± SD total serum cortisol level was 21.56 ± 8.71 μg/dL. The mean ± SD CBG level was 23.54 ± 8.33 mg/dL.
  
  
  CONCLUSIONS
  Salivary cortisol level can be used as a surrogate of free serum cortisol level in patients with septic shock with very good correlation. Salivary cortisol testing is noninvasive, easy to perform, and can be conducted daily.
authors.affiliation: Divisions of Critical Care, Pulmonary, and Sleep Medicine, The University of Texas Health Science Center at Houston, Houston, TX. Electronic address: rosa.m.estrada.y.martin@uth.tmc.edu.
authors.forename: Rosa M
authors.initials: RM
authors.lastname: Estrada-Y-Martin
authors.affiliation: Division of Endocrinology, Diabetes, and Metabolism, The University of Texas Health Science Center at Houston, Houston, TX.
authors.forename: Philip R
authors.initials: PR
authors.lastname: Orlander
mesh_terms: D018806:APACHE; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015415:Biomarkers / Q000097:blood / Q000378:metabolism*; D002352:Carrier Proteins / Q000097:blood; D002853:Chromatography, Liquid; D005260:Female; D006801:Humans; D006854:Hydrocortisone / Q000097:blood / Q000378:metabolism*; D007124:Immunoenzyme Techniques; D008297:Male; D013058:Mass Spectrometry; D008875:Middle Aged; D011863:Radioimmunoassay; D012044:Regression Analysis; D012463:Saliva / Q000737:chemistry*; D012772:Shock, Septic / Q000378:metabolism*
chemical_list: D015415:Biomarkers; D002352:Carrier Proteins; C027091:cortisol binding globulin; D006854:Hydrocortisone