The aim of the study is to characterize chromogranin A (CGA) in plasma and metanephrine (MN),  normetanephrine (NMN) in plasma or urine of pheochromocytoma patients immediately before  surgery to evaluate the usefulness of CGA and catecholamine metabolites in diagnosis of  pheochromocytoma tumors.

Deconjugated urinary catecholamine metabolites were determined by liquid chromatography with electrochemical detection. HPLC was performed after injection of 10 µl sample on a Synergi Polar – RP 80A stainless-steel column (150 x 3 mm I.D, 4-µm particle size) (Phenomenex, Torrance, USA) using a isocratic elution with acetonitril : water containig EDTA, KCl, NaH₂PO₄.2H₂O, H₃PO₄, 1-octanesulfonic acid and 1,4,7,10,13,16-hexaoxacyclooctadecane = 80 : 920 at a flow-rate of 0.6 ml/min. Catecholamines were isolated before HPLC by solid phase extraction of urine samples (100 µl) using Separon HEMA 1000 CM, 60 µm d_p (Tessek Ltd., Prague, Czech Republic) and Dowex 1x2 chloride form, 200-400 mesh (Sigma-Aldrich, Prague, Czech Republic). Elution profile of catecholamine metabolites was monitored by electrochemical detector Decade II (Antec, Leyden, Netherlands).

Immunoassay of plasmatic CGA, MN and NMN were performed using a commercially available kits of CIS bio international, France (CGA) and MetCombi Plasma Metanephrine/Normetanephrine (IBL Hamburg, Germany).

Clinical sensitivity for patients with pheochromocytoma (n=29) immediately before surgery was 90% using plasma CGA cut off value (COV) 150 µg/L, 79% for plasma NMN (COV 170 ng/L), 52% for plasma MN (COV 100 ng/L), 83% for urinary NMN (COV 400 µg/L) and 69% for urinary MN (COV 150 µg/L).    

Plasma CGA concentration was the effective marker of pheochromocytoma and it should be considered together with metanephrines in the diagnosis of this disease.

Acknowledgements. The work was supported by the grant No NT/12336-4 of the Internal Grant Agency, Ministry of Health, Czech Republic.