Primary Aldosteronism: Biochemical Workup from Screening to AVS to Post-Op Control on a Single Automated Platform

Presentation Number: SAT-0850
Date of Presentation: June 21st, 2014

Riia Karoliina Sustarsic*1, Jenny Manolopoulou2, Philipp Grimminger3, Chris Martin Roffe2, Martin Reincke4 and Martin Bidlingmaier5
1Medizinische Klinik und Poliklinik IV, Munich, Germany, 2Immunodiagnostic Systems Ltd., Boldon, United Kingdom, 3Medizinische Klinik und Poliklinik IV, Ludwig-Maximilian University, Munich, Germany, 4Klinikum der Universität München, Ludwig-Maximilian University, Munich, Germany, 5Klinikum der Universität München, Medizinische Klinik und Poliklinik IV, Munich, Germany

Abstract

Identifying patients with primary aldosteronism (PA) is essential for their optimal treatment. Screening by measuring aldosterone to renin ratio (ARR), confirmatory tests as the saline infusion test (Na-load) as well as differential diagnosis including adrenal venous sampling (AVS) for distinguishing between bilateral and unilateral disease rely strongly on reliable measurement of aldosterone, renin and cortisol. In this study, we demonstrate the potential of new automated assays on one analyzer (IDS-iSYS) during the diagnostic workup from screening to differential diagnosis and follow up after initiation of therapy. Initially samples had been measured by our current routine assays (Liaison Direct Renin and Cortisol, Siemens Coat-A-Count Aldosterone), and then by the new IDS-iSYS Aldosterone and Direct Renin assays. Cortisol in the AVS series was measured using the extremely rapid (7 minutes) IDS-iSYS Cortisol assay currently being developed. ARR was determined in 140 PA patients, 203 essential hypertensives (EH) and 261 normotensive subjects. ROC analysis revealed a cut-off at 1.1 ng/dL/µU/mL for discrimination between PA and EH when using the iSYS assays (sensitivity 98.6%, specificity 81.8%). In 9 out of the 140 PA patients we had access to screening samples, Na-load tests and AVS series (5 bilateral disease and 4 unilateral adenomas later treated by adrenalectomy) and also post-op samples. Na-load tests indicated PA in all 9 patients (iSYS aldosterone >5 ng/dL after Na-load). In samples from AVS series, iSYS measurements for cortisol and aldosterone showed concurrent results to the currently applied methods and led to the same diagnoses. Aldosterone was <10 ng/dL in all samples from patients who had adrenalectomy in line with successful treatment. Aldosterone was also normalized in the post-op Na-load tests (<5 ng/dL). Overall, the IDS-iSYS assays showed concurrence in diagnostic accuracy when compared to the routinely used assays. The availability of a very rapid cortisol assay provides advantages for the confirmation of correct placement of the catheter during AVS. The IDS-iSYS family of automated assays for aldosterone, renin and cortisol could become a valuable tool in the diagnosis and treatment of PA.

 

Disclosure: JM: Employee, Immunodiagnostic systems. CMR: Employee, Immunodiagnostic Systems Ltd.. MB: Consultant, Immunodiagnostic Systems Ltd., Investigator, Immunodiagnostic Systems Ltd.. Nothing to Disclose: RKS, PG, MR