An enzyme-linked immunosorbent assay (ELISA) for plasma testosterone

Area of Science:

• Biochemistry
• Immunology
• Analytical Chemistry

Background:

• Steroid hormone assays are crucial in clinical diagnostics.
• Existing methods like radioimmunoassay (RIA) have limitations regarding cost and isotope handling.
• Standardization of steroid hormone assays can be challenging.

Purpose of the Study:

• To develop and describe a rapid, single-extraction enzyme-linked immunosorbent assay (ELISA) for quantifying testosterone in plasma.
• To evaluate the performance of the developed ELISA compared to a testosterone RIA.
• To highlight the advantages of ELISA for routine steroid hormone analysis.

Main Methods:

• A single extraction method was employed using a 96-well microtitre plate.
• Testosterone was immobilized onto the plate via covalent bonding to bovine thyroglobulin and passive adsorption.
• The assay involved adding standards, samples, primary antibody (rabbit anti-testosterone), and a secondary antibody (peroxidase-labelled goat anti-rabbit IgG), followed by substrate addition and colorimetric detection.

Main Results:

• The developed ELISA demonstrated comparable specificity and precision to a testosterone RIA using a 125I-label.
• The ELISA offered a significantly quicker processing time compared to RIA.
• The assay proved to be more cost-effective than RIA, with added benefits in isotope management.

Conclusions:

• The described single-extraction ELISA is a viable, efficient, and cost-effective method for routine plasma testosterone measurement.
• ELISA presents advantages over RIA, particularly in terms of speed, cost, and avoidance of radioactive isotopes.
• This method is well-suited for implementation in standard steroid hormone diagnostic laboratories.