The major metabolites of catecholamines secreted by the adrenal glands in case of stress are metanephrine, epinephrine, normetanephrine and norepinephrine. These biomarkers are evaluated to determine urinary concentration of them in people with suspected pheochromocytoma. This disease is a very rare tumour and causes hypertension in nonfollowed cases. It is very important to accurately diagnose before surgical intervention and by looking at the catecholamine derivatives, it is possible to diagnose pheochromocytoma.