Parameters of captopril challenge test can predict results of other confirmatory tests for primary aldosteronism and propose the next test to be done

Abstract

In Japan, primary aldosteronism (PA) is diagnosed if any one of the captopril challenge test (CCT), saline infusion test (SIT), furosemide-upright test (FUP), and oral salt-loading test (OST) is positive. The present study aimed to investigate if parameters of CCT, the safest confirmatory test, could predict decisions of other tests and propose the next test to diagnose PA in CCT-negative patients. In a cross-sectional design, 142 patients, who were referred to our hospital for the scrutiny of PA and underwent at least two confirmatory tests, were enrolled. While 123 patients underwent all of the CCT, SIT, and FUP, the OST was successfully done in only six patients and excluded from further analyses. CCT parameters showing correlations of higher degrees with SIT and FUP parameters were selected, and their powers to predict SIT and FUP decisions were investigated by receiver operating characteristic analyses. Proposals of the next test based on the CCT parameters were validated with SIT and FUP decisions in subsets of CCT-negative patients divided by cutoffs of the CCT parameters. The plasma aldosterone concentration and plasma renin activity 60 min after the load of CCT (CCT60-PAC and CCT60-PRA) were selected, and CCT60-PAC ≤59.0 pg/mL and CCT60-PRA ≥1.05 ng/mL/h could predict negativities of SIT and FUP, respectively, with >95% specificities. Based on the validation, the present study suggested the SIT as the next test to be done if the CCT-negative patient belonged to the subset with CCT60-PAC >59.0 pg/mL and CCT60-PRA ≥1.05 ng/mL/h, otherwise the FUP should be selected.

Comparisons of plasma aldosterone and renin data between an automated chemiluminescent immunoanalyzer and conventional radioimmunoassays in the screening and diagnosis of primary aldosteronism

“…Because patients highly suspected of PA had been preferentially referred to our center, the prevalence of PA among our patients should be much higher than that among patients with hypertension in general practice. Actually, we previously reported that 128 (90.1%) of 142 patients, who received PA confirmatory tests for the scrutiny of PA in our center from April 2012 to December 2017, were PA patients [ 28 ]. On the other hand, patients whose PAC or PRA values had been measured in the scrutiny of adrenal incidentaloma, adrenal insufficiency, and renovascular hypertension were also included in the present study ( Fig 1 ).…”

“…However, the optimal cutoff value of basal CLEIA-ARR to detect PA patients was previously reported to be >6 ng/dL over pg/mL, where PA was diagnosed only by CCT [ 15 ]. Because 77% of CCT-negative patients were diagnosed with PA by SIT or FUP in our previous report [ 28 ], the cutoff value should be decreased to pick up CCT-negative PA patients. If PA had been diagnosed only by CCT in the present study, ten of 44 PA patients would have been diagnosed with non-PA and the optimal cutoff of basal CLEIA-ARR to detect PA would have increased to >3.47 ng/dL over pg/mL (Panel A of S3 Fig , S13 Table ).…”

Captopril challenge test in the diagnosis of primary aldosteronism: consistency between 1- and 2- h sampling

“…Variables derived from CCT included aldosterone concentration, aldosterone concentration inhibition rate, and ARR. Among them, aldosterone concentration has the best diagnostic performance and thus recommended ( 10 – 12 ). However, there is lack of consensus on the timing of blood sampling after captopril challenge ( 5 , 6 , 13 – 15 ).…”