PURPOSE: Primary aldosteronism (PA) can be classified into aldosterone-producing adenoma (APA) and idiopathic hyperaldosteronism (IHA) and is related to chronic inflammatory diseases. We compared lymphocyte-based inflammatory indices among patients with APA, IHA and essential hypertension (EH), and investigated the relationships between these indices and background factors in patients with PA. METHODS: A total of 186 patients (39 with APA, 48 with IHA, and 99 with blood-pressure-matched EH) were retrospectively included. Neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), and monocyte-to-lymphocyte ratio (MLR) were calculated as lymphocyte-based inflammatory indices. RESULTS: Lymphocyte count was lower in the APA group than in the IHA and EH groups. NLR and PLR were significantly higher in the APA group than in the IHA and EH groups. In the APA group, NLR correlated positively with plasma aldosterone concentration after the saline infusion test, while in the IHA group, NLR correlated positively with body mass index and negatively with flow-mediated dilation. Lymphocyte-based inflammatory indices did not differ significantly between KCNJ5-mutant and wild-type groups. NLR, MLR, and PLR remained unchanged from baseline to 1 week after adrenalectomy (ADX), but a cut-off baseline MLR of 0.18 was predictive of complete clinical success after ADX (sensitivity, 0.8095
specificity, 0.7222
area under the curve, 0.719). CONCLUSION: Lymphocyte-based inflammatory indices showed distinct patterns in patients with APA and IHA. This study provides a better understanding of the implications of complete blood cell counts in patients with PA.