A Clinical Prediction Score to Diagnose Unilateral Primary Aldosteronism

CONTEXT: Adrenal venous sampling is recommended to assess whether aldosterone hypersecretion is lateralized in patients with primary aldosteronism. However, this procedure is invasive, poorly standardized, and not widely available. OBJECTIVE: Our goal was to identify patients' characteristics that can predict unilateral aldosterone hypersecretion in some patients who could hence bypass adrenal venous sampling before surgery. DESIGN AND SETTING: A cross-sectional diagnostic study was performed from February 2009 to July 2010 at a single center specialized in hypertension care. PATIENTS: A total of 101 consecutive patients with primary aldosteronism who underwent adrenal venous sampling participated in the study. The autonomy of aldosterone hypersecretion was assessed with the saline infusion test. INTERVENTION: Adrenal venous sampling was performed without ACTH infusion but with simultaneous bilateral sampling. MAIN OUTCOME MEASURES: Variables independently associated with a lateralized adrenal venous sampling in multivariate logistic regression were used to derive a clinical prediction rule. RESULTS: Adrenal venous sampling was successful in 87 patients and lateralized in 49. All 26 patients with a typical Conn's adenoma plus serum potassium of less than 3.5 mmol/liter or estimated glomerular filtration rate of at least 100 ml/min/1.73 m2 (or both) had unilateral primary aldosteronism; this rule had 100% specificity (95% confidence interval, 91-100) and 53% sensitivity (95% confidence interval, 38-68). CONCLUSIONS: If our results are validated on an independent sample, adrenal venous sampling could be omitted before surgery in patients with a typical Conn's adenoma if they meet at least one of two supplementary biochemical characteristics (serum potassium<3.5 mmol/liter or estimated glomerular filtration rate ≥100 ml/min/1.73 m2).