Significance of Discordant Results between Confirmatory Tests in Diagnosis of Primary Aldosteronism

Context: Current clinical guidelines recommend confirmation of a positive result in at least one confirmatory test in the diagnosis of primary aldosteronism (PA). Clinical implication of multiple confirmatory tests has not been established, especially when patients show discordant results. Objective: The aim of the present study was to explore the role of 2 confirmatory tests in subtype diagnosis of PA. Design and Setting: A retrospective cross-sectional study was conducted at two referral centers. Participants and Methods: We identified 360 hypertensive patients who underwent both a captopril challenge test (CCT) and a saline infusion test (SIT) and exhibited at least one positive result. Among them, we studied 193 patients with PA whose data were available for subtype diagnosis based on adrenal vein sampling (AVS). Main Outcome Measure: The prevalence of bilateral subtype on AVS according to the results of the confirmatory tests was measured. Results: Of patients studied, 127 were positive for both CCT and SIT (double-positive), whereas 66 were positive for either CCT or SIT (single-positive) (n=34 and n=32, respectively). Altogether, 135 were diagnosed with bilateral subtype on AVS. The single-positive patients had milder clinical features of PA than the double-positive patients. The prevalence of bilateral subtype on AVS was significantly higher in the single-positive patients than in the double-positive patients. (63/66 [95.5%] vs 72/127 [56.7%], P<.01). Several clinical parameters were different between CCT single-positive and SIT single-positive patients. Conclusion: Patients with discordant results between CCT and SIT have a high probability of bilateral subtype of PA on AVS.