Endocrine Abstracts

Background: Primary aldosteronism (PA) is the commonest cause of secondary hypertension. Reported prevalence is about 30% in hypertensive population. Success of screening for PA in general practice (GP) is unknown. Expected challenges include laboratory access, transport issues and interfering medications.

Aims: We aimed to report prevalence of PA in a large primary care cohort, the correlation between GP and in-hospital ARR and to assess if a change in renin assay affected rates of positive ARR detection.

Methods: A retrospective analysis of individuals who had aldosterone-renin ratio (ARR) checked by their GP (GP-ARR) between January2012-December2021 was conducted. Reasons for testing and outcomes were retrieved from electronic records. Samples were assayed for aldosterone concentration ( pmol/l) and plasma renin activity (ng/ml/hour) before 2015 (positive if ARR > 1000) and for aldosterone (ng/dL) and direct renin concentrations (mU/l) (positive if ARR > 30) post-2015.

Results: In total 3408 samples from 2615 patients were received from GPs (13.5% rejected due to delayed transit time). Three hundred and thirty-two (12.7% of screened population) had positive GP-ARR (men 183 [55.1%]), median age 53 years [IQR 44-64]). Among positively screened, 232 (70%) were referred to secondary care. Among those referred to Endocrinology (n=200), 68% (60/88) had positive hospital-ARR and 33.5% (67/200) had confirmed PA and were treated with adrenalectomy (n=22) or mineralocorticoid antagonists (n=45). GP-ARR post-2015 renin assay change had higher positivity rate [16.7% (262/1568) vs 6.6% (70/1047), P<0.001].

Conclusions: Screening ARR for PA in primary care is feasible with low sample rejection rates and good concordance to in-hospital testing. Renin assay methods should be considered when analysing ARR outcomes. Over a quarter of patients with positive ARR results were not referred to secondary care highlighting the importance of increasing awareness of the benefit of investigation and treatment in PA to Primary Care colleagues.