The saline infusion test with mass spectrometric measurements of aldosterone in patients tested for primary aldosteronism

Christina Pamporaki; Hanna Remde; Georgiana Constantinescu; Lydia Kuerzinger; Carmina Teresa Fuss; Mirko Peitzsch; Manuel Schulze; Myron Lee; Jun Yang; Lisa Mueller; Tracy Ann Williams; Martin Reincke; Sven Gruber; Felix Beuschlein; Jacques Lenders; Graeme Eisenhofer

doi:10.1530/endoabs.99.RC3.5

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Endocrine Abstracts (2024) 99 RC3.5 | DOI: 10.1530/endoabs.99.RC3.5

ECE2024 Rapid Communications Rapid Communications 3: Adrenal and Cardiovascular Endocrinology | Part I (7 abstracts)

The saline infusion test with mass spectrometric measurements of aldosterone in patients tested for primary aldosteronism

Christina Pamporaki ¹ , Hanna Remde ² , Georgiana Constantinescu ¹ , Lydia Kuerzinger ² , Carmina Teresa Fuss ² , Mirko Peitzsch ³ , Manuel Schulze ⁴ , Myron Lee ⁵ , Jun Yang ⁶ , Lisa Mueller ⁷ , Tracy Ann Williams ⁷ , Martin Reincke ⁷ , Sven Gruber ⁸ , Felix Beuschlein ⁸ , Jacques Lenders ⁹ & Graeme Eisenhofer ¹

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¹Medical Faculty, University Hospital Carl Gustav Carus, Technische Universität Dresden, Department of Medicine III, Dresden, Germany; ²University Hospital, University of Würzburg, Division of Endocrinology and Diabetes, Würzburg, Germany; ³University Hospital Carl Gustav Carus, Technische Universität Dresden, Germany, Institute of Clinical Chemistry and Laboratory Medicine; ⁴Center for Interdisciplinary Digital Sciences, TU Dresden, Department Information Services and High Performance Computing, Dresden, Germany; ⁵Prince of Wales Hospital, Sydney, New South Wales, Australia; ⁶Hudson Institute of Medical Research, Clayton, Australia, Centre for Endocrinology and Metabolism, Melbourne, Australia; ⁷University Hospital, Ludwig Maximilian University Munich, Department of Medicine IV, Munich, Germany; ⁸University Hospital Zurich and the LOOP Zurich Medical Research Center, Zurich, Department of Endocrinology, Diabetology and Clinical Nutrition, Zurich, Switzerland; ⁹Radboud University Medical Center, Nijmegen, Department of Internal Medicine, Nijmegen, Netherlands

Background: Confirmation of primary aldosteronism (PA) with the saline infusion test (SIT) requires accurate measurements of plasma aldosterone, best achieved by mass spectrometry. Performance of the test and appropriate cut-offs remain inadequately defined.Design and methods: This prospective multicenter cohort study involved 451 patients with suspected PA who underwent a seated SIT. Among these, there were 90 and 76 in whom PA was respectively confirmed and excluded based on outcome assessment. Thirty-one patients who were not adrenalectomized underwent a repeat SIT at outcome assessment. Diagnostic performance and optimal cut-offs were determined from receiver operating characteristic (ROC) curves.

Results: Analysis of ROC curves indicated higher (P=0.020) areas under curves for the SIT than the aldosterone:renin ratio (0.968 vs 0.905). A cut-off of 141 pmol/l for the post-SIT aldosterone provided 100% sensitivity at a sub-optimal specificity of 87% for disease confirmation. A cut-off of 219 pmol/l provided improved specificity of 95%, though at a sensitivity of 87%. Among the 31 patients in whom the SIT was repeated, there were five (16%) in whom post-SIT aldosterone concentrations fell discordantly on both sides of the 141-219 pmol/l concentration range.

Conclusions: The SIT with mass spectrometric measurements of aldosterone provides superior performance over the ARR for diagnosis of PA, but is suboptimal as confirmatory test. Inaccuracy and discordance of the SIT indicate need for care in application and interpretation of the test. A cut-off for aldosterone above 219 pmol/l limits the false-positive rate to 5%, which may be suitable to select patients for adrenal venous sampling.