title: Saliva as a medium for aldosterone measurement in repeated sampling studies.
abstract: BACKGROUND
  Saliva is a readily available biological fluid, making it convenient in diagnosis of diseases and in multi-sampling protocols. Several salivary steroids give a useful index of free plasma levels. Increased incidence of primary aldosteronism (PA) in approximately 10% of the hypertensive population has increased interest in the mineralocorticoid aldosterone.
  
  
  METHODS
  A biotinylated-aldosterone tracer and a commercially available antibody are used in a time-resolved fluorescence immunoassay (TR-FIA) to measure salivary aldosterone (SA). Saliva was collected in various multi-sampling protocols: Investigation of diurnal rhythm in healthy and PA patients, ACTH stimulation test and posture test in healthy subjects.
  
  
  RESULTS
  Method validation showed a sensitivity of 19 ng/L and intra-/inter-assay precision between 7.2-10.1% and 8.7-15.7%, respectively. SA correlated significantly (y = 0.2995x +/- 0.01, r(2)=0.60) to plasma aldosterone measured by a commercial radioimmunoassay. SA (median; 95%CI) was at 111 (95-127)ng/L in PA (n=84) and 50 (44-56)ng/L in healthy subjects (n=60). After change in posture, aldosterone increased in both, saliva (57 (47-63)ng/L to 95 (84-117)ng/L) and plasma (26 (26-41)ng/L to 135 (110-181)ng/L). Peak levels were reached after 1h, and were higher in females than in males.
  
  
  CONCLUSIONS
  SA correlates well to plasma aldosterone and mirrors responses during conditions of stress. SA is significantly higher in PA, and the diurnal rhythm seen in the healthy is blunted in PA. We additionally found gender-dependent differential responses to posture, with higher increases in females. Measurement of aldosterone in saliva presents a useful and convenient method for application in multi-sampling studies.
authors.affiliation: Medizinische Klinik Innenstadt der Ludwig-Maximilians-Universität, 80336 Munich, Germany. Jenny.Manolopoulou@med.uni-muenchen.de
authors.forename: J
authors.initials: J
authors.lastname: Manolopoulou
authors.forename: P
authors.initials: P
authors.lastname: Mulatero
authors.forename: C
authors.initials: C
authors.lastname: Maser-Gluth
authors.forename: P
authors.initials: P
authors.lastname: Rossignol
authors.forename: A
authors.initials: A
authors.lastname: Spyroglou
authors.forename: Y
authors.initials: Y
authors.lastname: Vakrilova
authors.forename: S
authors.initials: S
authors.lastname: Petersenn
authors.forename: O
authors.initials: O
authors.lastname: Zwermann
authors.forename: P F
authors.initials: PF
authors.lastname: Plouin
authors.forename: M
authors.initials: M
authors.lastname: Reincke
authors.forename: M
authors.initials: M
authors.lastname: Bidlingmaier
mesh_terms: D000324:Adrenocorticotropic Hormone / Q000494:pharmacology; D000328:Adult; D000450:Aldosterone / Q000032:analysis* / Q000097:blood / Q000302:isolation & purification / Q000378:metabolism; D016477:Artifacts; D016022:Case-Control Studies; D002940:Circadian Rhythm; D005260:Female; D006801:Humans; D006929:Hyperaldosteronism / Q000097:blood / Q000378:metabolism / Q000503:physiopathology; D007118:Immunoassay; D008297:Male; D011187:Posture; D015203:Reproducibility of Results; D012463:Saliva / Q000737:chemistry* / Q000187:drug effects / Q000378:metabolism
chemical_list: D000450:Aldosterone; D000324:Adrenocorticotropic Hormone