Preoperative Renin Status Indicate the Clinical Outcome of Aldosterone-Producing Adenoma

Abstract

Primary aldosteronism is widely recognized as renin-independent hypersecretion of aldosterone and aldosterone-producing adenoma(APA) represents the typical clinical subtype. Plasma renin below detection levels was considered as an important indicator for PA, and the suppressed renin level after confirmatory tests was considered to be a prerequisite when interpreting the results of confirmatory tests, before making the diagnosis of PA. Strictly, there is no specific definition of suppressed renin level in patients with PA. Clinically, the renin level of patients with APA varied greatly within the low to normal range. However, the clinical characteristics and outcomes in patients with APA having different renin status remain unclear. This retrospective study included 274 patients with APA who underwent unilateral laparoscopic adrenalectomy with at least a 12-month follow-up postoperatively. Patients were classified into the following 2 groups: low renin and non-low renin groups measured at 8.2 mU/L, according to the widely used criteria(defined as plasma renin activity<1ng/ml/h≈PRC 8.2 mU/L). Only patients with two consecutive PRC less than 8.2 mU/L could be classified into the low renin group. For the screening test and the confirmatory tests, antihypertensive medication was withheld or changed according to the guideline. Chemiluminescence immunoassays showed the range of the plasma renin concentration as 0.4–41.5mU/L. Non-low renin APA patients (n=26) had higher presurgical SBP(p=0.028), DBP(p=0.001) and PRC post confirmatory tests(p<0.001), compared with low renin APA patients(n=248). There was no significant difference in baseline PAC(p=0.507) and serum potassium(p=0.348) between the two groups. Intriguingly, non-low renin APA patients had higher PAC(p<0.001) and PRC(p<0.001) and lower serum potassium(p<0.001) at follow-up. For non-low renin APA patients, the rate of complete clinical success after surgery was 42.3%, 25% lower than that of low renin APA patients. APA patients with PRC<0.5mU/L had the highest rate of complete clinical success(75%), followed by PRC 0.5~8.2 mU/L(65%) and 8.2~20 mU/L(50%), with the lowest rate in patients with PRC>20 mU/L(33%). Multivariable logistic regression showed that the presence of baseline PRC>8.2 mU/L was a strong independent predictor for the lack of complete clinical success[OR 3.7(1.5–8.9),p=0.004]. Plasma renin concentration is closely related to the clinical outcome of APA patients postoperatively. APA patients with higher baseline renin status are at high likelihood of persistent hypertension after surgery, in whom strengthened monitoring of blood pressure is necessary.