Endocrine Abstracts

Introduction: Pheochromocytoma is a rare tumor that develops from chromaffin cells of the adrenal medulla. In about 90% of cases, it is a benign tumor. Along with catecholamines, neuroendocrine cells of the adrenal medulla have the ability to produce various proteins and neuropeptides and secrete them into the blood. Among the known biologically active substances are: neuropeptide Y and human cocaine- and amphetamine-regulated transcript (CART).

Purpose: The aim of the study was to assess the usefulness of the determination of levels of neuropeptides: neuropeptide Y and CART in the diagnosis of patients with adrenal pheochromocytoma.

Material and methods: Patients were divided into 4 groups:

1. Patients with pheochromocytoma (n=51),

2. Patients with adrenal incidentaloma (n=23),

3. Patients with primary arterial hypertension (n=20),

4. Control group – healthy volunteers (n=52).

The following biochemical determinations were performed in all patients: plasma levels of metanephrine and normetanephrine, concentration of chromogranin A (CgA), neuropeptide Y (NPY) and human cocaine- and amphetamine-regulated transcript (CART). Biochemical determinations were made using the LC-MS/MS technique and immunochemical techniques (IRMA, ELISA) were used.

Results: Concentrations of the analyzed biomarkers: CgA, NPY and CART were significantly higher (P<0.001) compared to control groups (adenoma, primary hypertension and healthy subjects). Sensitivity, specificity and AUC indices of the analyzed biomarkers: CgA, NPY and CART were compared in the group of patients with pheochromocytoma vs. control groups: adenoma, primary hypertension and healthy subjects. Pheochromocytoma vs. adenoma: CgA: 84% sensitivity and 96% specificity (AUC 0.932); NPY: 80% sensitivity and 78% specificity (AUC 0.808) and CART: 43% sensitivity and 100% specificity (AUC 0.768). Pheochromocytoma vs. primary hypertension: CgA: 78% sensitivity and 100% specificity (AUC 0.945); NPY: 47% sensitivity and 100 specificity (AUC 0.615) and CART: 72% sensitivity and 85% specificity (AUC 0.797). Pheochromocytoma vs. healthy subjects (blood donors): CgA: 84% sensitivity and 98% specificity (AUC 0.923); NPY: 90% sensitivity and 86% specificity (AUC 0.897) and CART: 60% sensitivity and 49% specificity (AUC 0.403).

Conclsion: Among the analyzed biomarkers, CgA concentration determination presented the highest discriminant value between patients with pheochromocytoma and other study groups. Neuropeptide Y showed a high specificity between the analyzed groups, especially in the differential diagnosis of patients with adenoma and patients with essential hypertension.