Endocrine Abstracts

Introduction: Primary aldosteronism (PA) is the principal cause of arterial hypertension potentially treatable. The diagnosis is dependent of tests to identify patients who will benefit most with surgical treatment. ACTH stimulation test (AST) has been described as a useful confirmatory test, potentially identifying bilateral disease in patients without adrenal tumors.

Aim: Evaluate the AST in patients with hypertension and positive screening test for PA, which performed saline infusion test (SIT).

Methods: Retrospective observational study which included 12 patients that performed SIT and AST as confirmatory tests for PA, from May to October of 2017. IST consisted in infusion of 2,000 ml of 0.9% saline over 4 h. Was considered positive if plasmatic aldosterone concentration (PAC) ≥ 100 pg/ml, negative < 50 pg/ml and indeterminate between ≥50 pg/ml and <100 pg/ml. AST consisted in intravenous injection of 250 μg of tetracosactide acetate with measurements of PAC and plasmatic cortisol at every 30′ for 2 h and was considered positive if PACmax/cortisol ≥8.5. Bilateral disease was considered if PACmax/cortisol <18.2 and no adrenal tumor on CT scan.

Results: Median age was 54 years and 75% were female. Six patients had adrenal tumor on CT scan, four without tumor and two were unknown. Of patients with adrenal tumor, 1/3 were at right, 1/3 at left and 1/3 bilateral. All patients were treated with antihypertensive agents except 1. The median PACmax/cortisol was 10.5 (IQR 8.56–15.52). 8 reached PACmax at 60′, 3 at 30′ and 1 at 90′. Three patients had positive SIT and also positive AST (PACmax/cortisol=12.18–106.32). 2 patients had negative SIT and also negative result at AST (PACmax/cortisol = 5.04–8.49). Of seven patients with indeterminate result at SIT, the AST was negative in only 1 (PACmax/Cortisol = 7.4). Patients with positive AST presented higher PAC at SIT (P = 0.013) and lower K+ levels (P=0.02). Of patients without adrenal tumor, one had diagnosis excluded in both tests and the others presented PACmax/cortisol <18.2, consistent with bilateral PA.

Conclusion: This data show that results between SIT and AST in positive and negative cases were consistent. In cases where SIT was indeterminate, AST may be useful as a confirmatory test of PA. Patients without adrenal tumor presented an AST result consistent with bilateral PA, reducing the need for adrenal catheterization in this context. However, a larger sample is required for the validation of AST as a diagnostic test, as well as for assessing the benefits of PA treatment in patients with positive AST.