Roles of clinical criteria, computed tomography scan, and adrenal vein sampling in differential diagnosis of primary aldosteronism subtypes

Context: In patients with primary aldosteronism (PA), it is fundamental to distinguish between subtypes that benefit from different therapies. Computed tomography (CT) scans lack sensitivity and specificity and must be followed by adrenal venous sampling (AVS). Because AVS is not widely available, a list of clinical criteria that indicate the presence of an aldosterone-producing adenoma (APA) has been suggested. Objective and Design: The objective of the study was to test the sensitivity and specificity of the last generation CT scans, test prospectively the usefulness of clinical criteria in the diagnosis of APA, and develop a flow chart to be used when AVS is not easily available. Setting: Hypertensive patients referred to our hypertension unit were included in our study. Patients: Seventy-one patients with confirmed PA participated in our study. Intervention: All patients had a CT scan and underwent AVS. Main Outcome Measure: Final diagnosis of APA was the main measure. Results: A total of 44 and 56% of patients were diagnosed as having an APA and a bilateral adrenal hyperplasia (BAH), respectively. Twenty percent of patients with PA displayed hypokalemia. CT scans displayed a sensitivity of 0.87 and a specificity of 0.71. The posture test displayed a lower sensitivity and specificity (0.64 and 0.70, respectively). The distribution grades of hypertension were not significantly different between APA and BAH. Biochemical criteria of high probability of APA displayed a sensitivity of 0.32 and a specificity of 0.95. Conclusions: This study underlines the central role of AVS in the subtype diagnosis of PA. The use of the clinical criteria to distinguish between APA and BAH did not display a satisfactory diagnostic power.