Dehydroepiandrosterone (DHEA) is a steroid hormone produced by the adrenal glands. In the liver it is converted into Dehydroepiandrosterone sulfate (DHEA-S). In humans, DHEA-S levels are highest at age 20-25 and decline with advancing years, reaching 20- 30% of peak levels by age 70-80. DHEA-S shows the mainly androgen effects in the target tissues not until it is metabolized into the biologically active androgens (testosterone, dihydrotestosterone). A conversion into oestrogen is also possible. In the last third of pregnancy the adrenal glands of the foetus produce high levels of DHEA-S which functions as a precursor of the oestrogen synthesis of the mother. Only very little is known about the postnatal biological function of DHEA-S.

May be diagnosed by:   

• Determination of specific antibodies based on the ELISA technique
• Determination of specific antibodies based on the RIA-technique

DHEA-S ELISA:

Competitive immunoenzymatic colorimetric method for quantitative determination of DHEA-S in serum or plasma.

Principle of the Assay: 

Microtiter strip wells are precoated with anti-DHEA-S antibodies (solid-phase). DHEA-S in the sample competes with added horseradish peroxidase labelled DHEA-S (enzyme-labelled antigen) for antibody binding. After incubation a bound/free separation is performed by solid-phase washing. The immune complex formed by enzyme-labelled antigen is visualized by adding Tetramethylbenzidine (TMB) substrate which gives a blue reaction product. The intensity of this product is inversely proportional to the amount of DHEA-S in the sample. Sulphuric acid is added to stop the reaction. This produces a yellow endpoint colour. Absorption at 450 nm is read using an ELISA microwell plate reader.

Specific performance characteristics: 

Correlation with RIA performed on 25 samples is r = 0.996

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