Overnight Dexamethasone in Primary Aldosteronism Screening

Background Primary aldosteronism (PA) underlies or contributes to hypertension (HT) in up to 30% of patients. In the last two decades PA has been demonstrated to encompass mild forms, which do not meet established diagnostic criteria, yet are still clinically relevant. However, PA has been shown to be vastly underdiagnosed: less than 5% of patients from at-risk populations undergo screening. One of the main reasons for low PA screening prevalence is the recommendation of hypotensive therapy modification prior to hormonal assessment, i.e. withdrawal of medications interfering in the renin-angiotensin-aldosterone system (RAAS) (2016 Endocrine Society guideline, 2020 European Society of Hypertension consensus statement). On the other hand, in many instances, PA may be diagnosed despite treatment with RAAS-interfering drugs. Previous research showed efficacy in the diagnostic approach toward PA can be greatly improved by incorporating adrenocorticotropic hormone (ACTH) suppression. This was achieved by determining PA screening and confirmatory thresholds following a 2-day 2-mg/day dexamethasone (DXM) test. Patients diagnosed with PA by meeting these novel diagnostic criteria responded well to mineralocorticoid receptor antagonists. These two diagnostic approaches (work-up in patients receiving RAAS-interfering drugs along with ACTH suppression) have not been combined so far. Aim To generate and temporally validate PA screening thresholds (aldosterone-to-renin ratio, ARR, and aldosterone, Ald) among patients with HT receiving medications interfering in the RAAS by applying overnight ACTH suppression. Methodology The project received the consent of the local bioethics committee. A development cohort of n=80, and a confirmation cohort of n=80, amount to 240 participants total due to an expected withdrawal rate of 33%. Study participants will be enrolled in a single, tertiary-care endocrine hospital in one-day clinic setting among hypertensive patients undergoing hormonal examinations due to the presence of an adrenocortical lesion with radiological features of an adenoma or hyperplasia (ACA or AHA, respectively). Only patients with indications for further PA testing upon a positive, permissive ARR will be recruited for participation in the study. Further diagnostic procedures (both in the course of this research and clinically-indicated) will be conducted in an outpatient endocrine clinic. Exclusion criteria include non-viability for RAAS-interfering medication modification. Basal (1) ARR will be required for inclusion, while in the course of the project participants will undergo ARR measurements post-DXM on own (chronic) medications (2), pre- and post-DXM ARR upon partial modification of RAAS-interfering medications (3 and 4), and pre- and post-DXM upon temporary withdrawal of RAAS-interfering medications (5 and 6). An oral salt loading test, OSLT (one of established confirmatory PA tests), will be performed off interfering medications in all patients. Also, patients with a positive PA screening result will undergo either seated saline-infusion (SIT) and/or captopril challenge test (CCT) to confirm PA in a one-day clinic. Results of these confirmatory tests will be used as reference in determining sensitivity and specificity of PA screening thresholds on RAAS-interfering therapy regimens. Statistical analysis will be performed upon gathering clinical and hormonal data to determine thresholds for ARR, aldosterone and renin to suggest optimal (simple but more accurate than currently applied) PA screening criteria. Expected results The hypotheses of the project are 1. Eliminating the effect of ACTH on Ald release will result in better interpretability of ARR and/or renin and Ald thresholds, and 2. Complete withdrawal of RAAS-interfering medications is not required for PA screening upon ARR determination combined with ACTH suppression. The objective of the study is demonstrating that ARR measurement following overnight 1-mg DXM intake reduces the equivocal rate in interpreting the ARR measurement in PA screening compared to conventional ARR.