Laboratory diagnostics of pheochromocytoma

Abstract

Biochemical diagnosis of pheochromocytoma is based on the measurement of altered levels of normetanephrine and metanephrine in plasma or 24-hour urine samples. Plasma normetanephrine and metanephrine levels four times the upper limit of the normal value or metanephrine and normetanephrine excretion in urine above 700 and 1500 mcg/24 hours respectively makes further testing unnecessary and subsequent examination must be focused on the determination of tumour localization. In patients presenting with the above parameters elevated within the "grey zone", effect of medicinal products needs to be excluded and the diagnosis confirmed in the clonidine test or by the measurement of chromogranin A level.