MON-289 Relationship between confirmatory testing for primary aldosteronism and glomerular hyperfiltration

Abstract Disclosure: K. Naya: None. M. Kurajoh: None. Y. Nagata: None. Y. Miki: None. H. Uedono: None. T. Akihiro: None. Y. Imanishi: None. M. Emoto: None. Background: We have previously shown that elevated plasma aldosterone (PAC) levels are associated with glomerular hyperfiltration (increased glomerular filtration rate [GFR] and albuminuria) via efferent arteriolar vasoconstriction in patients with primary aldosteronism (PA). However, the relationship between confirmatory testing for PA and glomerular hyperfiltration remains unclear. Methods: This cross-sectional study included 33 Japanese patients with hypertension. GFR was measured using inulin clearance (GFR-Cin). Albuminuria was measured using a 24-hour urine collection. The saline infusion test (SIT), the captopril challenge test (CCT), and the furosemide upright test (FUP) were performed as confirmatory tests for PA. In cases where PAC was measured by radioimmunoassay, conversion to chemiluminescent enzyme immunoassay (CLEIA)-equivalent values was performed. Results: The median values for GFR-Cin and albuminuria were 74.0 ml/min and 10.2 mg/day, respectively, while those for SIT-PAC, CCT- aldosterone renin ratio (ARR), and FUP- plasma renin activity (PRA) were 30.3 pg/mL, 191, and 0.9 ng/mL/hr, respectively. Multiple linear regression analysis showed that both SIT-PAC and CCT-ARR were significantly associated with GFR-Cin and albuminuria. Furthermore, GFR and albuminuria were significantly different among the negative, borderline, and positive groups for both SIT and CCT, with higher values observed in the positive group, according to the Japan Endocrine Society guidelines. Similar results were obtained in the subgroup of 22 patients whose PAC was measured using the CLEIA method. Moreover, positive results for both SIT and CCT were individually associated with significantly higher GFR and albuminuria. In contrast, FUP-PRA was not significantly associated with either GFR-Cin or albuminuria. Conclusion: SIT-PAC and CCT-ARR, but not FUP-PRA, were shown to reflect glomerular hyperfiltration. These findings suggest that SIT-PAC and CCT-ARR may be sensitive indicators of glomerular hyperfiltration, and could inform future revisions to diagnostic criteria for PA. Presentation: Monday, July 14, 2025