ECE2023 Poster Presentations Adrenal and Cardiovascular Endocrinology (72 abstracts)
1University of Turin, Department of Medical Sciences, Turin, Italy; 2University of Turin, Clinical Biochemistry Laboratory, Turin, Italy
Background: The systematic use of confirmatory tests in the diagnosis of primary aldosteronism (PA) increases costs, risks and complexity to the diagnostic work-up. In light of this, some authors proposed aldosterone-to-renin (ARR) cut-offs and/or integrated flow-charts to avoid this step. Patients with resistant hypertension (RH), however, are characterized by a dysregulated renin-angiotensin-aldosterone system, even in the absence of PA. Thus, it is unclear whether those strategies might be applied with the same diagnostic reliability in the setting of RH. Aim of this study was to evaluate the predictive performance of the ARR in the diagnosis of PA in a prospective cohort of patients with true RH. More specifically, we set out to determine whether specific ARR cut-offs could allow the unambiguous identification of patients with PA, without the need of a confirmatory test.
Methods: We prospectively enrolled 129 consecutive patients diagnosed with true resistant hypertension and no other causes of secondary hypertension. All patients underwent full biochemical assessment for PA, including both basal measurements and saline infusion test (SIT). PA was diagnosed when the following conditions were met at the same time: baseline plasma aldosterone concentration (PAC) ≥ 15 ng/dL, ARR ≥ 40 (ng/dL)/(ng/mL/h), and PAC after SIT ≥ 10 ng/dL.
Results: 34/129 patients (26.4%) were diagnosed with PA. Among basal measurements, the parameter that provided the best diagnostic performance was ARR, which displayed a moderate accuracy in distinguishing patients with PA from those with essential RH (AUC=0.883). At multivariable logistic regression, serum potassium levels were identified as the second-best predictor of PA. After stratifying the patients according to the presence/absence of hypokalemia, an ARR > 238.4 (ng/dL)/(ng/mL/h) provided a 100% specificity for the diagnosis of PA in normokalemic patients, with a sensitivity of 25% (AUC=0.852). An ARR > 115.6 (ng/dL)/(ng/mL/h) provided a 100% specificity for the diagnosis of PA in hypokalemic patients, with a sensitivity of 64% (AUC=0.941).
Conclusions: Among normokalemic patients, there is a wide overlap in ARR values between those with PA and those with essential RH; the possibility to skip a confirmatory test should thus be considered with caution in this setting. A better discriminating ability can be seen in the presence of hypokalemia; in this case, ARR alone may be sufficient to skip confirmatory tests in a suitable percentage of patients.