The radioimmunoassay of dehydroepiandrosterone (DHEA) is a competition assay. Prior to the assay, samples (serum or plasma) are extracted with ethyl ether; the solvent is evaporated and the dry residues are re-dissolved in the recovery buffer of the kit.
The re-dissolved extracts and calibrators are then incubated with 125I-labeled DHEA, as tracer in antibody-coated tube. After incubation, the content of tubes is aspirated and the bound radioactivity is determined. A calibration curve is established and unknown values are determined by interpolation from the curve.