Endocrine Abstracts

Introduction: Primary hyperaldosteronism (PA) is known to be an underdiagnosed secondary cause of hypertension in the population, with an estimated prevalence of up to 29% in patients with resistant hypertension. In patients with adrenal incidentalomas (AI), PA is estimated to be 1.1-10% and is lower than rates seen for detection of cortisol hypersecretion and pheochromocytoma. The diagnostic pathway is complicated by factors including confounding medications, co-morbidities and scarcity of adrenal venous sampling (AVS) and functional imaging.

Methods: Retrospective review of data from patients with AI who undertook screening for PA (2018-2023) was conducted. Data were collected for demographics, comorbidities, imaging, biochemistry and management outcomes.

Results: 833 patients with AI had biochemical screening for PA. 63 (7.6%) had aldosterone: renin ratio (ARR) results potentially indicative of PA and required further investigation. Of those with ARR < 1000, 439 (57.0%) were on medications that could cause a false negative. 8 (1.8%) had medications stopped prior to initial testing. Of the 63 with possible PA, 49 (77.8%) were on confounding medications. 15 (30.6%) were on medications which could cause a false positive. 28 (44.4%) had further testing with saline infusion, AVS or both. Of those with ARR >2000, 51.9% had hypokalemia and 96.3% had hypertension versus 27.8% and 77.8% respectively for those with ARR between 1000-2000. 37 (58.7%) were subsequently diagnosed with PA, representing 4.4% of the entire cohort, and received either medical or surgical intervention or both. 35 (55.6%) with indicative ARR results, did not have further investigations for various reasons.

Conclusions: In this real-world cohort, we identified a significant proportion of AI patients with biochemical suspicion of PA on confounding medications, potentially resulting in missed diagnoses. Additionally, several patients did not undergo further testing. Therefore, our study suggests multiple possible causes leading to underdiagnosis of PA in patients with AI.