LAUSR

INTRODUCTION Pheochromocytoma is a hormonally active tumour originating from neuroendocrine cells of the adrenal medulla. Chromogranin A (CgA) and peptide proSAAS belong to the family of granins and are present in neuroendocrine cells of adrenal medulla, from where they are released to circulation, along with catecholamines. The aim of this study was to assess the usability of proSAAS peptide assay in patients with adrenal pheochromocytoma. MATERIAL AND METHODS 23 patients (13 females and 10 males) with adrenal pheochromocytoma (benign in 18 patients and malignant in 5) confirmed by histopathology examination, and 35 blood donors as a control group. Plasma free metanephrines, CgA, and proSAAS peptide levels were measured in all participants. RESULTS CgA and proSAAS levels in the group of pheochromocytoma patients vs. the control were: 209 ng/mL and 0.8 ng/mL vs. 59 ng/mL and 0.3 ng/mL (p < 0.001), respectively. The following sensitivity and specificity indexes were obtained from ROC curves for CgA: 83% and 92%, respectively, and for the proSAAS peptide: 39% and 88%, respectively. The combination of 2 parameters: normetanephrine and proSAAS (96% and 100%) had a high diagnostic value, and the value of all determined parameters together (metanephrine, normetanephrine, CgA, and proSAAS) was 100%. CONCLUSION A single determination of the proSAAS peptide level is associated with a rather low diagnostic value. But collective determination of CgA and proSAAS may be an additional, valuable tool in biochemical diagnostics of pheochromocytoma.