Urinary aldosterone-to-active-renin ratio: A useful tool for predicting resolution of hypertension after adrenalectomy in patients with aldosterone-producing adenomas

BACKGROUND The purpose of this study was to determine the preoperative clinical and biological factors that predict the clinical outcomes after surgery, in subjects with aldosterone-producing adenomas (APAs). METHODS Fifty-eight patients (mean age 52 +/- 11 years) with APA were followed up for 43 +/- 13 months after they had undergone unilateral adrenalectomy. The subjects were classified as "cured" (n = 23) if the blood pressure (BP) was < 140/90 mm Hg without postoperative medication, "normalized" (n = 20) if BP was < 140/90 mm Hg with antihypertensive therapy, and "uncontrolled" (n = 15) if a BP of <= 40/90 mm Hg was not achieved despite intensive therapy. RESULTS The cured patients had a significantly lower mean preoperative age, cardiac mass, and serum creatinine (P < 0.001) than the other subjects. The main independent predictors of surgical curability were: age (P < 0.01), low serum potassium (P < 0.0001), and the urinary aldosterone-to-active-renin UAAR) ratio (P < 0.008). Among the hormonal parameters, the UAAR ratio provided the best area under the receiver operating-characteristics curve (0.802 (confidence interval (CI) 95%:0.676-0.944)). For a cutoff value of 15, the positive and negative predictive values of the UAAR ratio were 85 and 92%, respectively. In the study population as a whole, surgical treatment restored the age-systolic BP (SBP) relationship (P < 0.006), which was insignificant before surgery. CONCLUSIONS Although all the subjects showed lowering of BP after surgery, and the age-BP relationship was restored, the long-term cure rate of APA subjects was 40%. The UAAR ratio, by comparison with other classical hormonal features of primary aldosteronism, was the best independent predictor of the cure of hypertension after adrenalectomy.