Evaluation of Biochemical Conditions Allowing Bypass of Confirmatory Testing in The Workup of Primary Aldosteronism: A Retrospective Study in a French Hypertensive Population.

The diagnostic workup for primary aldosteronism includes a screening step using the aldosterone-to-renin ratio (ARR) and a confirmatory step based on dynamic testing of aldosterone secretion autonomy. International guidelines suggest that precise clinical and biochemical conditions may allow the bypassing of the confirmatory step, however, data which validate hormone thresholds defining such conditions are lacking. At our tertiary center, we retrospectively examined a cohort of 173 hypertensive patients screened for PA by the ARR, of whom 120 had positive screening and passed a saline infusion test (SIT) or a captopril challenge test (CCT). Fifty-nine had PA, including 34 Conn adenomas and 25 with idiopathic aldosteronism (IA). Using a threshold of 160 pmol/l, post-SIT plasma aldosterone concentration (PAC) identified PA with 86.4% sensitivity, 94.7% specificity, and a negative predictive value of 92.3%. Of those subjects with a high ARR and a PAC above 550 pmol/l, 93% had a positive SIT, while 100% of subjects with a high ARR, but a PAC under 240 pmol/l had a negative SIT. Our results thus validate the biochemical conditions defined in the French and US guidelines for bypassing the confirmatory step in the workup for PA diagnosis.