Seated Saline Suppression Test for Lateralizing Primary Aldosteronism
Alexander A. Leung, Raj Padwal, Gregory L. Hundemer, Erik Venos, David J.T. Campbell, Daniel T. Holmes, Dennis J. Orton, C. Benny So, Stefan Przybojewski, Cori Caughlin, Janice L. Pasieka, Rabi Doreen, Gregory A. Kline
Abstract
BACKGROUND: Confirmatory testing to identify lateralizing primary aldosteronism (PA) is of uncertain benefit. METHODS: Blinded clinical trial where patients with high-risk features for PA underwent the seated saline suppression test (SSST). All patients received adrenal vein sampling, where lateralization was defined by an aldosterone/cortisol ratio ≥3:1 comparing the dominant versus the nondominant sides. The primary outcome was the overall diagnostic accuracy of the SSST in identifying lateralizing PA using postinfusion aldosterone concentrations of ≥140 pmol/L (5.0 ng/dL) and ≥280 pmol/L (10.1 ng/dL) with immunoassay, and ≥162 pmol/L (5.8 ng/dL) with liquid chromatography/tandem mass spectrometry. RESULTS: A total of 160 patients completed the trial. Lateralizing PA was diagnosed in 98 patients (61.3%). The overall diagnostic accuracy of the SSST using an aldosterone cutoff of ≥140 pmol/L (5.0 ng/dL) and ≥280 pmol/L (10.1 ng/dL) was 64.4% (95% CI, 56.4-71.8) and 67.5% (95% CI, 59.7-74.7), respectively. A positive result was equivocal at the lower cutoff of ≥140 pmol/L (5.0 ng/dL; positive likelihood ratio, 1.1 [95% CI, 1.0-1.3]) and minimally informative at the higher cutoff of ≥280 pmol/L (10.1 ng/dL; positive likelihood ratio, 1.9 [95% CI, 1.3-2.7]). Negative results modestly ruled against lateralization using cutoffs of ≥140 pmol/L (5.0 ng/dL) and ≥280 pmol/L (10.1 ng/dL; negative likelihood ratio, 0.3 [95% CI, 0.1-0.9]; and 0.5 [95% CI, 0.3-0.7], respectively). The SSST properties were similar with liquid chromatography/tandem mass spectrometry. CONCLUSIONS: Aldosterone suppression testing is unreliable for anticipating adrenal vein sampling outcomes. The SSST may misinform diagnostic-treatment decisions. REGISTRATION: URL: https://www.clinicaltrials.gov; Unique identifier: NCT04422756.