1977 Volume 53 Issue 6 Pages 797-809
A simplified direct radioimmunoassay system for serum aldosterone measurement was developed by using radio iodine-labeled aldosterone and highly specific antiserum to aldosterone.
8-anilino-1-naphthalene sulfonic acid (ANS) was used to prevent the binding of aldosterone to serum proteins. Polyethylene glycol was used to separate the antibody-bound aldosterone from the free aldosterone as the precipitant.
The minimum measurable concentration of aldosterone is 30pg/ml of serum by short incubation method (at 25°C for 3hr incubation) and 15pg/ml of serum by long incubation method (at 4°C for 20hr incubation) respectively.
Present radioimmunoassay eliminates extraction of the aldosterone from serum and chromatographic separation procedures, and requires only 0.1ml of serum sample for assay.
The intra-assay precision was C. V. 6.9% (average of 4 samples) and the inter-assay precision was C. V. 10.7% (average of 4 samples).
There is an excellent correlation between the extraction method and this direct method in serum aldosterone value obtained (correlation coefficient, 0.96). The normal value was 36.8±25.9 pg/ml (recumbent) and 113.6±61.5pg/ml (upright).
