title: Immunoassay of 7-hydroxysteroids: 2. Radioimmunoassay of 7alpha-hydroxy-dehydroepiandrosterone.
abstract: High sensitivity radioimmunoassay of 3beta, 7alpha-dihydroxy-5-androsten-17-one (7alpha-OH-DHEA) has been developed and evaluated. The method is based on polyclonal rabbit antisera raised against 19-O-(carboxymethyl)oxime bovine serum albumin conjugate and bridge- and position homologous [(125)I]iodotyrosine methyl ester as a tracer. Sensitivity of the assay amounted to 3.12 fmol (0.95 pg)/tube, precision as a mean intra- and interassay coefficient of variation was 7.1 and 10.6%, respectively, and the average recovery of the analyte added to steroid-free serum was 110%. Out of the steroids occurring in human serum which may interfere with the assay, the only important cross-reactants were dehydroepiandrosterone and 3beta, 7beta-dihydroxy-5-androsten-17-one (7beta-OH-DHEA) with cross-reactivities of 1.95 and 1.16%, respectively. The levels of free (unconjugated) 7alpha-OH-DHEA have been determined in 29 sera from healthy volunteers (23 females and 6 males), and from 48 patients (43 females and 5 males) in which dehydroepiandrosterone and its sulfate (DHEA/S) had been measured for various endocrinopathies. The levels in healthy subjects ranged from 0.21 to 6.57 (mean 2.33+/-1.50) nM, while those of the patients from 0 to 5. 99 (mean 1.46+/-1.52) nM. The levels of 7alpha-OH-DHEA in patients significantly correlated with those of DHEA and its sulfate.
authors.affiliation: Institute of Endocrinology, Národní tr. 8, 116 94, Praha, Czech Republic. olapcik@endo.cz
authors.forename: O
authors.initials: O
authors.lastname: Lapcík
authors.forename: R
authors.initials: R
authors.lastname: Hampl
authors.forename: M
authors.initials: M
authors.lastname: Hill
authors.forename: L
authors.initials: L
authors.lastname: Stárka
mesh_terms: D000818:Animals; D002851:Chromatography, High Pressure Liquid; D003429:Cross Reactions / Q000276:immunology; D003687:Dehydroepiandrosterone / Q000031:analogs & derivatives* / Q000097:blood; D005260:Female; D006801:Humans; D006914:Hydroxysteroids / Q000032:analysis* / Q000097:blood; D008297:Male; D011817:Rabbits; D011863:Radioimmunoassay / Q000379:methods*; D051381:Rats; D012044:Regression Analysis; D012680:Sensitivity and Specificity
chemical_list: D006914:Hydroxysteroids; D003687:Dehydroepiandrosterone; C003587:7-hydroxydehydroepiandrosterone