title: Assessing estradiol in biobehavioral studies using saliva and blood spots: simple radioimmunoassay protocols, reliability, and comparative validity.
abstract: We developed simple, reliable, and highly sensitive assay modifications of commercially available radioimmunoassay kits to measure estradiol in saliva and blood spot specimens. The saliva assay has average intra- and interassay coefficients of variation (CV) of 6.45 and 9.01%, with average analytical and serial dilution recoveries 100.65 and 89.25%. The blood spot assay has average intra- and interassay CVs of 7.57 and 8.22%, with analytical and serial dilution recoveries of 80.50 and 108.50%. The analytical sensitivity ranges of the saliva (0.25-7.50 pg/ml) and blood spot (2. 00-375 pg/ml) assays are sufficient to determine levels in the majority of pre- and postpubertal males and females. Blood spot assay results are correlated with serum estradiol levels for adult males, r (17) = 0.73, and females, r (18) = 0.96. In contrast, the serum-saliva correlation is only modest for adult females, r (14) = 0.60, and not significant for adult males. Substitution of blood spot assay results for serum values underestimates the known serum estradiol-behavior correlation by only 3.45%, whereas substitution of saliva assay results for serum values underestimates the association by 37.55%. The findings have important implications for the use and potential misuse of noninvasive measures of estradiol in studies of health and human development.
authors.affiliation: Behavioral Endocrinology Laboratory, Pennsylvania State University, University Park, Pennsylvania 16802, USA.
authors.forename: E A
authors.initials: EA
authors.lastname: Shirtcliff
authors.forename: D A
authors.initials: DA
authors.lastname: Granger
authors.forename: E B
authors.initials: EB
authors.lastname: Schwartz
authors.forename: M J
authors.initials: MJ
authors.lastname: Curran
authors.forename: A
authors.initials: A
authors.lastname: Booth
authors.forename: W H
authors.initials: WH
authors.lastname: Overman
mesh_terms: D000328:Adult; D000375:Aging / Q000097:blood / Q000378:metabolism; D001519:Behavior / Q000502:physiology*; D002648:Child; D004958:Estradiol / Q000032:analysis* / Q000097:blood* / Q000502:physiology; D005069:Evaluation Studies as Topic; D005260:Female; D006801:Humans; D008297:Male; D011627:Puberty / Q000097:blood / Q000378:metabolism; D011863:Radioimmunoassay / Q000379:methods* / Q000592:standards; D011933:Reagent Kits, Diagnostic; D012463:Saliva / Q000737:chemistry*
chemical_list: D011933:Reagent Kits, Diagnostic; D004958:Estradiol