SAT-358 The Sequential Order Effect on Confirmatory tests in Primary Aldosteronism

Abstract T. Ichijo: None. N. Ikeda: None. H. Ishiodori: None. K. Takuma: None. F. Kasahara: None. K. Ikehara: None. M. Higa: None. It is well known the primary aldosteronism (PA) is most common endocrinological hypertension and accounted for approximately 10% among all hypertension population, and it develops cardiovascular disease more frequently than blood pressure matched essential hypertension. Several confirmatory tests are recommended by Endocrine Society’s guideline including saline infusion test (SIT) and captopril challenge test (CCT). It doesn’t mention how many should be done nor those sequential order to be performed if several tests are planned.Thus, we investigated 576 cases of PA diagnosed by those 2 tests in our hospital since 2007, including 204 males and 372 females, and their mean age was 55.9 ± 11.3 years old. We evaluated the effect of order on those results of the confirmatory tests, comparing 2 groups; patients performed CCT after SIT (SIT-CCT) and those in opposite order (CCT-SIT). We interpreted CCT positive when aldosterone-renin ratio (ARR) after 50mg of captopril administration at 60 or 90 minutes. SIT is performed by 2L of saline infusion for 4 hours in the recumbent position and interpreted SIT positive when plasma aldosterone concentration (PAC) shows more than 60 pg/ml at 4 hours. We evaluated ARR after 60 and 90 minutes in CCT and the positive ratio between 2 groups, SIT-CCT group and CCT-SIT group.In our results, plasma renin activities (PRAs) at 60 and 90 minutes in CCT were significantly lower among SIT-CCT group than CCT-SIT group, 0.50 ± 0.52 vs. 0.68 ± 0.76, p=0.0317; 0.51 ± 0.49 vs. 0.66 ± 0.61ng/ml/hr, p=0.0207, respectively. PACs at basal, 60 and 90 minutes in CCT were also significantly lower among SIT-CCT group than CCT-SIT group, 9.6 ± 5.1 vs. 12.9 ± 8.4, p=0.0002; 8.5 ± 4.7 vs. 11.7 ± 8.4, p=0.004; 8.7±6.2 vs. 12.0±10.0ng/dl, p=0.0002, respectively. In the other hand, the basal PRAs, ARRs at 60 and 90 minutes showed no significant difference, nor the positive ratio of CCT (p=0.0778), either, although it was still tendency to increase to the positive ratio of CCT. The reason of increase the ratio thought to be stronger and longer suppression in PRAs than PAC.In conclusion, our result revealed no significant difference was shown on CCT positive ratio in our patients, though it still showed a tendency to increase the positive ratio with both suppression of PRAs and ARRs. Thus, the order of confirmatory tests may affect the diagnosis of PA, and those should be solved issues what order of confirmatory tests is required and how long should be leaved between the confirmatory tests. Saturday, June 1, 2024