Inflammatory and nutritional indices in patients with pheochromocytoma

Aims: Pheochromocytoma is characterized by catecholamine excess, which may influence immune regulation and metabolic pathways. However, the relationship between catecholamine activity, systemic inflammation, and immune-nutritional status remains incompletely understood. This study aimed to evaluate inflammatory and nutritional indices in patients with pheochromocytoma and to investigate their association with tumor size and plasma metanephrine levels.Methods: In this retrospective study, 39 patients with pheochromocytoma were compared with 24 age-, sex-, and body mass index-matched healthy control subjects. Complete blood count parameters and inflammation-based indices, including neutrophil-to-lymphocyte ratio (NLR), systemic immune-inflammation index (SII), Prognostic Nutritional Index (PNI), and Controlling Nutritional Status (CONUT) score, were analyzed. Correlation analyses were performed to assess the relationships between inflammatory indices, plasma metanephrine levels, and tumor size.Results: Patients with pheochromocytoma had significantly higher WBC, neutrophil, and platelet counts than controls. SII was significantly elevated, whereas NLR, CONUT, and PNI did not differ between groups. Fasting glucose levels were higher in the pheochromocytoma group, while lipid parameters were comparable. Correlation analyses demonstrated PNI was negatively correlated with both tumor size and plasma metanephrine levels. SII showed positive correlations with NLR and PNI, and CONUT was positively correlated with NLR.Conclusion: Pheochromocytoma is associated with systemic inflammatory activation, as reflected by elevated leukocyte parameters and increased SII. Although overall nutritional indices were not significantly altered, the inverse association between PNI and tumor burden suggests that catecholamine excess may adversely affect immune-nutritional status. These findings highlight the complex immune-metabolic interplay in pheochromocytoma.