A commercially available assay kit for determining aldosterone concentration in non-extracted rat serum

A commercially available assay for aldosterone that requires no extraction was found to be valid without modification for rat serum. The assay was performed in duplicate on as little as 0.5 cc of rat serum and gave linear results from 5 ng/dl to 500 ng/dl, (i.e., the physiological range of the rat). Samples above 150 ng/dl had to be diluted in this assay. The cost per sample if performed in duplicate and in batches was approximately one dollar. We found that this assay, which was developed for and is marketed for determining aldosterone concentration in human samples, offered a cost effective assay for aldosterone determination in the rat.