Outcomes After Unilateral Adrenalectomy in Asymmetrical Bilateral Primary Aldosteronism

BACKGROUND: Lateralization by adrenal vein sampling (AVS) is the gold standard for diagnosis of unilateral primary aldosteronism. Aldosterone production from the contralateral gland suggests bilateral disease; however, little is known regarding outcomes from patients with grossly elevated (but asymmetrical) contralateral aldosterone production after unilateral adrenalectomy. METHODS: A retrospective chart review was performed of cases from the Calgary AVS database with (1) successful AVS (selectivity index ≥3 bilaterally after cosyntropin stimulation); (2) lateralization by AVS (lateralization index ≥3), stimulated or unstimulated; (3) absence of contralateral suppression (contralateral suppression index ≥2 on the nondominant side) stimulated or unstimulated; and (4) underwent unilateral adrenalectomy guided by AVS lateralization. Postsurgical outcomes were classified per PASO criteria. RESULTS: A total of 29 cases met inclusion criteria and underwent unilateral adrenalectomy with postsurgical outcomes available. Of patients with biochemical follow-up data, 20 of 27 had a complete biochemical response and 3 of 27 a partial response (median follow-up time of 10.3 weeks, interquartile range, 4.0–18.3). Four of 29 patients had a complete clinical response, while 18 of 29 patients had a partial clinical response (median follow-up time of 27.3 weeks, interquartile range, 10.7–35.6), such that 75% of patients had either complete or partial clinical response to unilateral adrenalectomy. CONCLUSIONS: In patients with bilateral (elevated contralateral suppression index) but asymmetrical primary aldosteronism, unilateral adrenalectomy can achieve positive biochemical and clinical outcomes in the short to mid-term. Elevated contralateral suppression index should not necessarily preclude recommendation of unilateral adrenalectomy in patients with lateralized primary aldosteronism, though longer-term studies are needed to clarify the rates of disease recurrence and benefits of a debulking procedure.