Interference in the Measurement of Plasma 11-Hydroxycorticosteroids Caused by Spironolactone Administration

Abstract

The Mattingly method for estimating plasma "cortisol" concentration involves measurement of the fluorescence in strong sulfuric acid of materials extracted from plasma by methylene chloride. In three patients without adrenocortical disease and in one normal volunteer, administration of spironolactone was shown to be associated with a prompt, striking and sustained increase in plasma Mattingly fluorogens. Similar increases followed administration of spironolactone to a patient with Addison's disease, indicating that the response was not due to an alteration in endogenous steroid metabolism. Furthermore, direct in vitro addition of spironolactone to plasma yielded increased values in the Mattingly assay. Hence, artifactual elevations in the concentrations of plasma "cortisol," as measured by the Mattingly method, are to be expected in patients receiving spironolactone.