EVALUATION OF A NEW DIAGNOSTIC TEST FOR PRIMARY ALDOSTERONISM

Abstract

Objective: Primary aldosteronism (PA) is the most common form of endocrine hypertension. Currently, diagnosis comprises a screening test based on the aldosterone –to-renin ratio (ARR), followed by a confirmatory test to verify autonomous aldosterone secretion. However, available confirmatory tests (fludrocortisone, saline infusion) are laborious or relatively expensive. For this reason, the non-invasive Captopril test has been widely used despite its lower specificity. Recently, a new overnight screening test (DCVT) has been proposed, using oral administration of combined blockers of RAAS (renin–angiotensin–aldosterone system). The aim of the study was to assess the performance of DCTV in the diagnosis of PA in patients in whom the diagnosis was confirmed by the established Captopril test. Design and method: A total of 94 subjects with hypertension were investigated over a 2-year period. To confirm PA diagnosis all the patients underwent the Captoptil challenge test, as previously described. In addition, in all participants the DCVT was performed (patients received 2 mg Dexamethasone, 50 mg Captopril and 320 mg Valsartan at midnight and an extra dose of 50 mg Captopril 1 h before blood sampling in the next morning). Results: In the whole group of patients, 37 were diagnosed with PA on the basis of Captopril test cut-offs. The remaining 57 patients were considered to have essential hypertension. There was no significant difference in the main characteristics (age, sex, BMI, blood pressure, fasting blood glucose, lipids) between the two groups, except for potassium which was lower in patients with PA (p < 0.001). The areas under the receiver–operator characteristics curves for the post DCTV-aldosterone and post-DCVT ARR were 0.88 and 0.82, respectively. The optimal cutoff value for post DCTV- aldosterone was 262 pmol/l, which yielded a sensitivity and specificity of 83% and 75% respectively. Conclusions: In conclusion, DCVT is an reasonable alternative to the more complex invasive confirmatory tests in the PA diagnosis. Similarly to Captopril test, DCVT is safe and much easier to perform, so it may serve as a feasible alternative, despite slightly lower performance indices. When interpreting the results of DCVT, post- DCTVT aldosterone is recommended compared to post-DCVT ARR.