Measurement of serum levels of dehydroepiandrosterone sulfate: a comparison of radioimmunoassay and enzymatic analysis

Dehydroepiandrosterone sulfate (DHEAS) and unconjugated dehydroepiandrosterone (DHEA) are secretory products of the adrenal cortex. Measurement of serum levels of these steroids is of increasing epidemiologic interest, since low serum concentrations of DHEAS or DHEA have been associated with an increased risk of dying of cardiovascular disease or of developing cancer. Radioimmunoassays (RIAs) are the most convenient systems for the measurement of serum DHEAS concentrations in multiple samples. However, using sera from four individuals we show that different RIA kits provide quite different estimates of serum DHEAS concentrations. Moreover, these results do not always agree with the serum concentrations determined by an independent chromatographic and enzymatic reference method. The results highlight the need for an independent method of determining DHEAS levels in sera that can provide guidance in selecting an appropriate RIA, and in interpreting the results.