title: The determination of 18-hydroxycorticosterone in saliva and plasma: comparison with aldosterone and glucocorticoids.
abstract: A radioimmunoassay (RIA) for 18-hydroxycorticosterone (18OHB) is described using antibodies raised against 18OHB-3-CMO conjugated to bovine albumen and an iodine-125 labelled ligand. Extracts of plasma and saliva required thin-layer chromatographic purification prior to RIA. These assays have been validated in terms of precision, accuracy and specificity. The concentration of 18OHB in saliva is approx 20% of that in plasma and the two values are correlated. Thus, in a series of 20 healthy subjects the saliva and plasma concentration were 169 +/- 92 and 904 +/- 621 pmol.l-1 respectively with r = 0.72 (P less than 0.001). When the diurnal patterns of 18OHB, aldosterone and glucocorticoid (cortisol + cortisone) concentrations in saliva were investigated the patterns of 18OHB and aldosterone were usually similar though the 18OHB:aldosterone ratio can vary considerably. These and similar data suggest that the secretion of 18OHB and aldosterone are not completely synchronous. Our results show that saliva is a suitable body fluid in which to estimate 18OHB concentration and this measurement gives a useful reflection of the plasma 18OHB concentration. This technique should facilitate the investigation of the physiological role of this compound.
authors.affiliation: Department of Chemical Pathology, St Mary's Hospital Medical School, London, England.
authors.forename: C Y
authors.initials: CY
authors.lastname: Lee
authors.forename: J D
authors.initials: JD
authors.lastname: Few
authors.forename: V H
authors.initials: VH
authors.lastname: James
mesh_terms: D015069:18-Hydroxycorticosterone / Q000032:analysis* / Q000097:blood; D000324:Adrenocorticotropic Hormone / Q000494:pharmacology; D000328:Adult; D000367:Age Factors; D000450:Aldosterone / Q000032:analysis / Q000097:blood; D002675:Child, Preschool; D002855:Chromatography, Thin Layer; D002940:Circadian Rhythm; D003345:Corticosterone / Q000031:analogs & derivatives*; D005938:Glucocorticoids / Q000032:analysis / Q000097:blood; D006801:Humans; D008297:Male; D009043:Motor Activity; D011863:Radioimmunoassay; D012463:Saliva / Q000032:analysis*
chemical_list: D005938:Glucocorticoids; D000450:Aldosterone; D015069:18-Hydroxycorticosterone; D000324:Adrenocorticotropic Hormone; D003345:Corticosterone