ISSN 1470-3947 (print) | ISSN 1479-6848 (online)

Endocrine Abstracts (2019) 63 P31 | DOI: 10.1530/endoabs.63.P31

Predictors of bilateral and unilateral primary aldosteronism: a retrospective observational study

Takuya Ishikawa1, Hirotsugu Suwanai1, Hironori Abe1, Keitaro Ishii1, Hajime Iwasaki1, Fumiyoshi Yakou1, Mariko Ito1, Jumpei Shikuma1, Ryo Suzuki1, Kazuo Hara2, Takashi Miwa1, Tomoko Takamiya3, Shigeru Inoue3, Kazuhiro Saito4 & Masato Odawara1

1Tokyo Medical University, Department of Diabetes, Metabolism and Endocrinology, Tokyo, Japan; 2Jichi Medical University Saitama Medical Center, Department of Medicine, Division of Endocrinology and Metabolism, Saitama, Japan; 3Tokyo Medical University, Department of Preventive Medicine and Public Health, Tokyo, Japan; 4Tokyo Medical University, Department of Radiology, Tokyo, Japan.

Primary aldosteronism is a frequent cause of secondary hypertension, with early diagnosis being important for appropriate treatment and minimizing the risk of organ damage due to excessive aldosterone. Treatment, however, varies for unilateral and bilateral primary aldosteronism, with oral aldosterone antagonist being the treatment of choice for the bilateral form and adrenalectomy, for the unilateral form. As surgical treatment for unilateral primary aldosteronism is effective, early and accurate differentiation of the unilateral and bilateral forms is important. However, there has not been established an alternative diagnostic method except adrenal vein sampling to distinguish them. In this study, we undertook a retrospective comparison of the clinical and serum markers between patients with bilateral and unilateral primary aldosteronism, diagnosed by adrenal vein sampling, to identify factors strongly associated with the unilateral form. We also evaluated the outcomes of surgical treatment in unilateral cases to confirm the usefulness of adrenalectomy. The prospective study group was formed of patients with suspected PA, based on findings of juvenile hypertension, hypokalemia and resistance to antihypertensive treatment. Of these, 249 completed the Captopril challenge, saline infusion and the furosemide upright tests for PA diagnosis, with a positive diagnosis in 239 patients. 96 out of 239 patients underwent adrenal vein sampling for localization of primary aldosteronism diagnosis at our hospital between 2010 and 2018. On univariate analyses, systolic blood pressure, plasma aldosterone concentration, and the aldosterone-to-renin ratio were significantly higher in the unilateral than in the bilateral group, whereas the serum potassium level was lower. On multivariate analysis, Captopril challenge test results and serum potassium level were retained as independent predictors of unilateral primary aldosteronism. Adrenalectomy was effective in lowering systolic blood pressure, plasma aldosterone concentration, and serum potassium levels, as well as decreasing the number of therapeutic drugs used. Therefore, unilateral primary aldosteronism is differentiated from bilateral aldosteronism by a higher plasma aldosterone concentration and aldosterone-to-renin ratio, indicative of excessive aldosterone being secreted, with serum potassium and Captopril challenge test results being reliable diagnostic predictors as it resulted good sensitivity and specificity.