Contralateral Suppression at Adrenal Venous Sampling Is Associated with Renal Impairment Following Adrenalectomy for Unilateral Primary Aldosteronism

BACKGROUND: Adrenal venous sampling (AVS) is performed to distinguish the subtype of primary aldosteronism (PA). The clinical implication of contralateral suppression (CS; aldosterone/cortisol(nondominant)<aldosterone/cortisol(peripheral)) at AVS remains unclear. We aimed to investigate the clinical significance of CS and its impact on postoperative outcomes after unilateral adrenalectomy. METHODS: In this retrospective observational multi-center study, we analyzed PA patients who underwent both successful adrenocorticotropin hormone-stimulated AVS and unilateral adrenalectomy. Successful cannulation was defined as the selectivity index (cortisol(adrenal)/cortisol(peripheral)) ≥3. Clinical and biochemical outcomes after unilateral adrenalectomy were evaluated based on the international Primary Aldosteronism Surgical Outcome consensus. RESULTS: Among 263 patients analyzed, 247 had CS (93.9%). Patients with CS had lower serum potassium levels, higher plasma aldosterone concentration, higher aldosterone-to-renin ratio (ARR), and larger adenoma size than those without CS. Those with CS showed significantly higher lateralization index than those without CS (P<0.001). Although postoperative blood pressure and ARR significantly decreased in those with CS, clinical and biochemical outcomes were comparable in both groups. When the cut-off value of age was determined using receiver operating characteristic (ROC) analysis, patients aged ≥50 years old with contralateral suppression index (CSI; the ratio between aldosterone/cortisol(nondominant) and aldosterone/cortisol(peripheral)) ≤0.26 had greater odds ratio (6.43; 95% confidence interval, 1.30 to 31.69) of incident chronic kidney disease than those aged <50 years with CSI >0.26 after adjusting for other factors. CONCLUSION: CS may not predict postoperative clinical and biochemical outcomes in subjects with unilateral aldosterone excess, but it is associated with postsurgical deterioration of renal function in subjects over 50 years with CSI ≤0.26.