Abstract 353: Clinical Significance of Low Normal Serum Potassium Concentrations in the Diagnosis of Aldosterone Producing Adenoma

Abstract

Introduction The number of PA patients is gradually increasing, because screening has been become active in general clinicians. Plenty of patients with PA, however, still have been undiagnosed and threatened by cardiovascular morbidities. Especially, patients with Aldosterone Producing Adenoma(APA) should be screened as early as possible to prevent from them. Therefore, we believed that useful marker not to miss APA has been hoped by general clinicians. Recent studies showed that serum potassium (sK) showed significantly lower in APA than in primary hypertension (PH), although the prevalence of hypokalemia is getting lower than previous in PA patients. In the present study, we retrospectively investigated to find the optimal cut-off value (CV) of sK among all hypertensive patients referred to our hospital for detecting APA, on the hypothesis that it might be significantly lower in APA than in PH instead of the administration of any hypertensive agents. Patients All 169 patients undergone adrenal vein sampling and diagnosed with APA by pathological exams after surgery were recruited. PA was screened by elevated value of ARR (>20; PAC in ng/dl and PRA in ng/ml/hr) at baseline, and diagnosis was confirmed by the elevated ARR(>20) after loading captopril. PH (n=194) was defined as below 20 of baseline ARR and ruled out other secondary hypertensions. Study protocol Patients were compared their parameters in each combination of agents shown as next. 1. All agents. 2. Only ACE-I and/or ARB were essentially included. 3. Diuretics and beta blockers were included in addition to agents of Study 2. In each study, Calcium channel blockers and alpha blockers were optionally allowed. ROC curve analysis was performed for each study. Results 1. The best CV was 28.1 in ARR. The sensitivity (SE) and specificity (SP) were 86% and 85%, respectively. 2. The best CV was 3.7mM in sK. SE and SP were 83% and 98%, respectively. 3. The best CV was 3.8mM in sK. SE and SP were 79% and 91%, respectively. In each study, the rate of above 140 mM in serum sodium (sNa) was 98%(165 of 169), 97%(29 of 30), and 98%(65 of 66), respectively. Conclusion For effective detection of APA, we propose that patients whose sK are below 3.8mM and sNa are above 140mM with ACE-I/ARB treatments should be referred to special clinicians.