SUN-251 - Targeted Treatment of Confirmed and Suspected Primary Aldosteronism in Bangladeshi Patients: A Prospective Outcomes Study

Background: Primary aldosteronism (PA) is the most common cause of endocrine hypertension but remains substantially under-diagnosed, particularly in low- and middle-income countries where aldosterone suppression tests and adrenal vein sampling are often unavailable. When suppression tests are available, those who do not meet current criteria for PA are often diagnosed with low-renin hypertension which may represent part of the same spectrum of renin-independent aldosteronism and has been reported to respond to mineralocorticoid receptor antagonists (MRAs). We sought to evaluate the clinical and biochemical response to MRA therapy in patients with suspected PA, irrespective of aldosterone suppression test results, in a tertiary hospital in Bangladesh.

Methods: In this prospective observational study, consecutive adults with hypertension referred to a tertiary Endocrine Hypertension Clinic (September 2022 – December 2024) were screened for PA using the aldosterone-to-renin ratio (ARR). Patients with an elevated ARR >50 pmol/mIU underwent saline suppression testing (SST) and/or captopril challenge testing (CCT). PA was confirmed if 4-hour post-SST aldosterone exceeded 170 pmol/L or 2-hour post-CCT aldosterone exceeded 333 pmol/L. Patients were treated with spironolactone irrespective of the suppression test results, unless adrenal CT indicated a clear-cut unilateral adenoma together with florid biochemical aldosteronism. Adrenal vein sampling was not available. Treatment response was collected at six months, including biochemical response (defined as complete when renin concentration >10 mU/L and serum potassium > 3.5 mmol/L without supplementation) and clinical response (defined as complete when blood pressure < 140/90 mmHg on spironolactone monotherapy).

Results: Of 456 patients screened for PA, 186 (40.8%) had an elevated ARR of whom 108 met the formal diagnostic criteria for PA based on either the SST or CCT; 96% of patients with elevated ARR had low renin < 12 mIU/l. Eight patients underwent adrenalectomy while the remaining 178 patients received spironolactone. Among 175 medically treated patients with six-month follow-up data available, 130 (74.3%) achieved a complete biochemical response and 93 (53.1%) achieved a complete clinical response. There was substantial overlap in baseline aldosterone, renin and ARR across clinical and biochemical response categories. Among patients with a complete clinical response, 53% and 90% did not meet the PA diagnostic thresholds for SST and CCT, respectively.

Conclusions: MRA therapy was effective in patients with suspected PA, regardless of their aldosterone suppression test results. Elevated ARR and low renin identify patients likely to benefit from MRA, supporting a pragmatic and cost-effective approach to treating aldosterone-mediated hypertension, particularly in resource-limited environments.

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