Enzyme-Linked Immunosorbent Assays for Determination of Plasma Aldosterone Using Highly Specific Polyclonal Antibodies

Two enzyme-linked immunosorbent assays were established and compared for the estimation of plasma aldosterone. In the first method immobilized aldosterone-protein complexes on the ELISA plates compete with aldosterone to be determined for the binding of certain amount of anti-aldosterone antibodies. The sensitivity of this method depends on the protein carrier used to conjugate with aldosterone. In the second method, anti-aldosterone antibodies adsorbed on ELISA plates compete for binding of known amount of the enzyme-labeled aldosterone and aldosterone to be determined. The highly specific rabbit anti-aldosterone antibodies were obtained by injection of aldosterone-oxime thyroglobulin. The detection limit of aldosterone in both methods ranged between 2–20 pg. The proposed assays are suitable for the determination of aldosterone in biological fluids compared with other reported ELISA assays, as well as with RIA.