Non-chromatographic radioimmunoassay procedure for urinary aldosterone

We describe a sensitive, specific, and simple procedure for measuring aldosterone in human urine, which requires no chromatographic purification before quantification by radioimmunoassay but does include hydrolysis and extraction steps. Rabbit anti-aldosterone serum is sued, generated against aldosterone-18,21-dihemisuccinate coupled to human serum albumin. The antibody cross reacted little with other structurally related steroids that are in human urine. Our procedure was validated by comparing values for urinary aldosterone in human urine, with and without preliminary purification by chromatography on either paper (y = 0.92x + 2.9; r = 0.99; p less than 0.01) or (Sephadex LH-20) column (y = 0.98x + 0.6; r = 0.99; p less than 0.01). Values by our procedure also correlated well (y = 1.03x - 0.8; r = 0.99; p less than 0.01) with those obtained with use of a validated commercial "kit" for urinary aldosterine. All reagents for the proposed method are available commercially.