title: A novel radioimmunoassay of 16alpha-hydroxy-dehydroepiandrosterone and its physiological levels.
abstract: 16alpha-Hydroxy-dehydroepiandrosterone (16alpha-OH-DHEA) belongs to the products of extensive DHEA metabolism in mammalian tissues. It is a precursor of 16alpha-hydroxylated estrogens, increased levels of which are associated with autoimmune disorders. A highly specific radioimmunoassay of unconjugated 16alpha-OH-DHEA was developed and evaluated. Polyclonal rabbit antisera were raised against 3beta,16alpha-dihydroxy-17,19-dione-19-O-(carboxymethyloxime) and 3beta,16alpha-dihydroxy-7,17-dione-7-O-(carboxymethyloxime) BSA conjugates. Two methods were used for preparation of the conjugates. Homologous radioiodinated derivatives with tyrosine methyl ester were prepared as tracers. While antisera to 7-CMO cross-reacted with DHEA as much as by 58%, the cross-reaction of the chosen antiserum prepared via 19-oxogroup by micellar conjugation technique with 16beta-OH-DHEA was only 0.13% and with all other structurally related steroids, including DHEA were lower than 0.01%. The detection limit was 0.017 pmol (5.7 pg)/tube, the average intra- and inter-assay coefficients of variation were 8.2 and 11.4%, respectively. Mean recovery of serum spiked with 16alpha-OH-DHEA varied between 80 and 110%, the results were independent on sample dilution. 16alpha-OH-DHEA concentrations in 18 randomly selected sera, including 6 samples from patients with thyroid cancer were compared with results obtained by earlier GC-MS method. Physiological levels of 16alpha-OH-DHEA in 316 sera (184 females and 132 males) analyzed so far varied between 0.0 and 1.86 nmol/l.
authors.affiliation: Institute of Endocrinology, Prague, Czech Republic.
authors.forename: Ludmila
authors.initials: L
authors.lastname: Zamrazilová
authors.forename: Hana
authors.initials: H
authors.lastname: Kazihnitková
authors.forename: Oldrich
authors.initials: O
authors.lastname: Lapcík
authors.forename: Martin
authors.initials: M
authors.lastname: Hill
authors.forename: Richard
authors.initials: R
authors.lastname: Hampl
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D002648:Child; D002675:Child, Preschool; D003687:Dehydroepiandrosterone / Q000031:analogs & derivatives* / Q000032:analysis / Q000097:blood / Q000737:chemistry / Q000276:immunology; D005260:Female; D006801:Humans; D007106:Immune Sera / Q000032:analysis; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D008991:Monitoring, Physiologic; D009994:Osmolar Concentration; D011817:Rabbits; D011863:Radioimmunoassay / Q000379:methods*; D012680:Sensitivity and Specificity
chemical_list: D007106:Immune Sera; C011277:16-hydroxydehydroepiandrosterone; D003687:Dehydroepiandrosterone