Patients with pheochromocytoma exhibit low aldosterone renin ratio

Background Plasma renin activity (PRA) is generally increased in patients with pheochromocytoma (PCC) due to low circulating plasma volume and activation of β-1 adrenergic receptor signaling. However, there has been no study on the aldosterone renin ratio (ARR) in patients with PCC. To elucidate the issue, this study aimed to determine the PRA, plasma aldosterone concentration (PAC), and ARR in patients with PCC and compare them with those in patients with subclinical Cushing’s syndrome (SCS) and non-functioning adrenal adenoma (NFA). Methods In this retrospective single-center, cross-sectional study, 67 consecutive patients with adrenal tumors (PCC (n =18), SCS (n =18), and NFA (n =31)) diagnosed at Kobe University Hospital between 2008 and 2014 were enrolled. Results PRA was significantly higher in patients with PCC than in those with SCS and NFA (2.1 (1.3~2.8) vs. 0.7 (0.5~1.8) and 0.9 (0.6~1.4) ng/mL/h; p =0.018 and p =0.025). Although PACs were comparable among the three groups, ARR was significantly lower in patients with PCC than in those with SCS and NFA (70.5 (45.5~79.5) vs. 156.0 (92.9~194.5) and 114.9 (90.1~153.4); p =0.001 and p 1.55 ng/mL/h showed a sensitivity of 70.0% and specificity of 80.6%. Interestingly, ARR