A Radioimmunoassay for Serum Dehydroepiandrosterone

Abstract

A radioimmunoassay for serum dehydroepiandrosterone has been developed by using the anti-DHEA antiserum. After DHEA-7α-³H was added to 0.2 to 1.0ml of serum and 1ml of water for recovery, DHEA was extracted with methylene chloride, and the extract was evaporated to dryness. The residue was applied to paper chromatography. The eluates and DHEA-7α-³H which was added to determine the % free of DHEA were evaporated to dryness, and the residues were incubated with the antiserum containing pepsin treated human immune serum globulin and bovine serum albumin at 4°C overnight. Ammonium sulfate was used to separate free from bound DHEA. The accuracy, precision and specificity were satisfactory. The sensitivity was 300pg per sample. The blank value could not be differentiated from zero. Although the antiserum reacted with the other 3β-OH-Δ⁵-steroids as well as with DHEA, complete separation of DHEA from the other 3β-OH-Δ⁵-steroids was achieved chromatographically. Serum DHEA levels in normal subjects and their responses to ACTH stimulation and dexamethasone suppression were evaluated by using the radioimmunoassay.