Significance of computed tomography and serum potassium in predicting subtype diagnosis of primary aldosteronism

Context: The number of centers with established adrenal venous sampling (AVS) programs for the subtype diagnosis of primary aldosteronism (PA) is limited. Objective: Aim was to develop an algorithm for AVS based on subtype prediction by computed tomography (CT) and serum potassium. Design: A multi-institutional retrospective cohort study in Japan. Patients: A total of 1591 patients with PA were classified into four groups according to CT findings and potassium status. Subtype diagnosis of PA was determined by AVS. Main Outcome Measure: Prediction value of the combination of CT findings and potassium status for subtype diagnosis. Results: The percentages of unilateral hyperaldosteronism on AVS were higher in patients with unilateral disease on CT than those with bilateral normal results on CT (50.8% vs 14.6%, P, 0.01), and these percentages were higher in those with hypokalemia than those with normokalemia (58.4% vs 11.5%, P, 0.01). The prevalence and odds ratio for unilateral hyperaldosteronism on AVS were as follows: bilateral normal on CT with normokalemia, 6.2% (reference); unilateral disease on CT with normokalemia, 23.8% and 4.8 [95% confidence interval (CI), 3.1 to 7.2]; bilateral normal on CT with hypokalemia, 38.1% and 9.4 (95% CI, 6.2 to 14.1), and unilateral disease on CT with hypokalemia, 70.6% and 36.4 (95% CI, 24.7 to 53.5). Conclusions: Patients with PA with bilateral normal results on CT and normokalemia likely have a low prior probability of a lateralized form of AVS and could be treated medically, whereas those with unilateral disease on CT and hypokalemia have a high probability of a lateralized form of AVS.