Confirmatory testing in primary aldosteronism

Abstract

Context: Although confirmatory testing to verify aldosterone excess is a key step in the diagnosis of primary aldosteronism (PA), there is no consensus as to whether it is always needed and which of the tests need to be performed. Objective: The objective of this study was to investigate the diagnostic significance of confirmatory tests in PA. Design and Patients: In group A, 120 hypertensive patients who had positive case detection using the aldosterone to renin ratio (ARR) were subjected to at least one confirmatory test: thecaptopril challenge test (CCT), furosemide upright test (FUT), or saline infusion test (SIT). Among group A, 57 patients underwent all three confirmatory tests (group B), and 57 patients were differentiated as having either unilateral or bilateral PA based upon adrenal venous sampling, adrenal scintigraphy, and/or adrenal surgery (group C). Results: The percentages of patients with positive CCT and FUT were 86 and 87% in group A, 88 and 88% in group B, and 96 and 94% in group C, respectively. The percentage of patients with positive SIT results was lower than that with other tests (P< 0.01). The percentage of patients with positive results for the three tests was higher in patients with baseline ARR of at least 1000 or plasma aldosterone concentration (PAC) of at least 250 pg/ml than in those with lower ARR or PAC in all three groups. Conclusions: Most patients with positive case detection also had positive results on the CCT and FUT, especially when ARR was at least 1000 or PAC was at least 250 pg/ml under renin suppresion. Confirmatory testing for PA may not be needed in all patients with positive case detection. Copyright © 2012 by The Endocrine Society.