[Value of 24-hour urinary aldosterone in diagnosis and classification of primary hyperaldosteronism]

Objective: To investigate the clinical application value of 24-hour urinary aldosterone(UEA) in diagnosis and classification of primary aldosteronism(PA). Methods: A retrospective analysis was conducted on 282 hypertensive patients admitted to the Endocrinology Department of Xiangya Third Hospital of Central South University from December 2020 to December 2023. Thirty-nine patients with secondary hypertension, included secondary hypertension caused by renal parenchymal hypertension, renal vascular hypertension, cortisol hypersecretion, pheochromocytoma and paraganglioma, thyroid and parathyroid diseases and aortic diseases, were excluded. A total of 243 patients were finally included, including 130 males and 113 females, with the age of [M(Q₁,Q₃)]50.0(41.0, 56.5) years. The patients were divided into PA group (n=135) and primary hypertension group (n=108) based on the cause of hypertension. Plasma aldosterone concentration (PAC) and renin activity (PRA) were measured at 2 hour of standing position. Twenty-four-hour urine samples were collected for determination of aldosterone by liquid chromatography tandem mass spectrometry. The area under receiver operating characteristic (ROC) curve was drawn to evaluate the value of 24-hour UEA and 24-hour UEA to renin ratio (UARR) in the screening of PA. Ninety-seven patients with PA subtypes identified based on adrenal vein sampling (AVS) and/or surgical pathology and postoperative follow-up results were enrolled. They were divided into unilateral primary hyperaldosteronism (UPA) group (n=54) and idiopathic hyper aldosteronism(IHA) group (n=43). ROC was drawn to evaluate the value of serum potassium, standing PAC, aldosterone to renin ratio (ARR), 24-hour UEA and UARR in the diagnosis of PA typing. Results: Serum potassium and PRA in PA group were lower than those in primary hypertension group (all P<0.01), while systolic blood pressure, diastolic blood pressure, blood sodium, urine potassium, PAC, ARR, UEA and UARR in PA group were higher than those in primary hypertension group (all P<0.05). The area under ROC curve for 24-hour UEA diagnosis of PA was 0.848(95%CI:0.799-0.897), the cut-off value was 8.42 μg/d, sensitivity and specificity were 99.3% and 59.3%, respectively. The area under the ROC curve was 0.986(95%CI:0.977-0.996), with sensitivity and specificity of 100.0% and 88.0%, respectively. The area under the ROC curve of UARR was 0.988(95%CI: 0.980-0.997), the cut-off value was 20.3 (μg/d)/(ng·ml^-1·h^-1), sensitivity and specificity were 90.4% and 83.2%, respectively. There was no significant difference between UARR and ARR (P>0.05). Subgroup analysis shows that the areas under the ROC curves for the diagnosis of 24-hour UEA and UARR in differentiating UPA from IHA are 0.772(95%CI:0.679-0.865) and 0.664(95%CI:0.539-0.764), respectively. The sensitivity of 24-hour UEA>16.8 μg/d and UARR>135.0 (μg/d)/(ng·ml^-1·h^-1) to predict UPA was 59.3% and 61.1%, respectively, and the specificity was 86.0% and 74.4%, respectively. Conclusions: Twenty-four-hour UEA can provide reference for clinical screening and diagnosis of PA. If combined with renin activity detection, it can provide screening value comparable to ARR. In addition, 24-hour UEA and UARR can be used as better predictors of PA typing diagnosis.