Endocrine Abstracts

Introduction: Primary aldosteronism (PA) is an important, potentially curable cause of hypertension (HT) with higher risk of cardiovascular events than essential HT. In 2007, a standardized PA work-up protocol was introduced in Landspitali University Hospital (LUH), housing the only endocrine department in Iceland. The aim of this study is to review characteristics, test results and histopathology for patients diagnosed with PA in 2012-2016 in LUH.

Methods: Charts for PA-patients aged ≥18, diagnosed in 2012–2016 in LUH, were retrospectively reviewed. Screening was considered positive if s-aldosterone and/or 24-h urinary aldosterone excretion was increased and s-renin decreased. Diagnosis was confirmed if s-aldosterone increased by >140 pmol/l on saline infusion test (SIT) performed by a 4-hour intravenous infusion of isotonic saline, 500 ml/h. Thereafter, patients underwent a CT-scan and adrenal venous sampling (AVS) for distinguishing unilateral (UD) from bilateral disease (BD). Adrenalectomy was offered if UD was diagnosed.

Results: Thirty-six patients were diagnosed with PA during the period; 19 males and 17 females. All had s-aldosterone >300 pmol/l on morning screening and 12 had an elevated 24-h urinary aldosterone (n=23). Median (range) s-aldosterone after SIT was 311 pmol/l (202-1715). By the end of 2016, 10 had a confirmed UD (32%), 21 BD (68%) and 5 were awaiting AVS. Six out of 10 UD underwent adrenalectomy by the end of 2016 and all had a cortical adenoma on histopathological examination. CT-scan showed unilateral adrenal nodule in 15 patients, 8 of whom had UD by AVS on that same side (positive predictive value 0.53).

Conclusions: This study indicates that PA is an important cause of HT in Iceland with equal gender distribution. Bilateral hyperplasia proved to be a more frequent cause than cortical adenoma which is consistent with prior Icelandic results from 2007–2011. Interestingly, no-one was diagnosed with unilateral hyperplasia during the study period.