Radioimmunoassay of aldosterone in plasma and urine:

1. A rapid, robust, accurate and sensitive radioimmunoassay procedure is described for the measurement of plasma and urinary aldosterone. 2. A new, simple method is validated for the separation of free from bound moieties which has general applicability and which involves the measurement of free steroid by direct extraction into toluene-based liquid scintillator. 3. A new method, of validated specificity, is described for the measurement of the acid-labile metabolite of aldosterone in urine which avoids the necessity for preliminary chromatographic purification.