The Ratio of Plasma Aldosterone Concentration to Potassium in Adrenocorticotropin Stimulation Test is a Possible New Index for Diagnosis of Aldosterone-producing Adenoma in Patients with Primary Aldosteronism

Abstract

Primary aldosteronism (PA) is the most common form of secondary hypertension, and is characterized by high plasma aldosterone concentration (PAC) and low plasma renin activity (PRA), refractory hypertension, and occasional hypokalemia. Reliable parameters are required to identify aldosterone-producing adenoma (APA) in patients with PA, because APA is treatable with surgical resection if localization of aldosterone hypersecretion can be determined by adrenal venous sampling (AVS). The purpose of this study is to summarize the results of AVS in our institute and to evaluate the diagnostic accuracy of various parameters with adrenocorticotropic hormone (ACTH) stimulation test in identifying probable APA among patients with PA. Eighty-one patients with PA were admitted to Shinshu University Hospital from April 2009 to March 2013, and 59 patients who underwent AVS were included in the study. PAC and aldosterone to potassium ratio (APR) in ACTH stimulation tests were examined in 28 patients. Receiver operating characteristic (ROC) curve analysis was used to evaluate diagnostic accuracy. The response of PAC to ACTH in the probable APA group was stronger than that in the others. In ROC curve analysis, the area under the curve (AUC) of APR (PAC_30min/potassium) for diagnosis of probable APA was 0.9840 with an optimal cutoff value＞102.6 corresponding to sensitivity and specificity of 94.1% and 90.9% for diagnosis of APA, respectively. This study indicated that APR after the ACTH stimulation test may be a useful and accurate parameter in cases of PA. In cases with APR≥100 after ACTH stimulation, AVS is strongly recommended for localization of aldosterone hypersecretion.