Metanephrines
Sample: Urine 24 hrs in HCl (See Sample instructions)
Schedule: Ten Days (HPLC-Electrochemical)
Units: umol 24 hrs (or umol/mmol creatinine for random sample)
Range: Metanephrine (Meadrenaline) < 1.2 umol/24 hrs Normetanephrine (Normetadrenaline) < 2.5 umol/24 hrs Total Metanephrines < 3.7 umol/ 24hrs
Remarks: Catecholamines are the hormones of the adrenal medulla: Dopamine, Norepinephrine (Noradrenaline) and Epinephrine (Adrenaline) whereas Metanephrines are their metabolites: 3-Methoxytyramine, Normetanephrine (Normetadrenaline) and Metanephrine (Metadrenaline), respectively. The final products of the metabolism of both Catecholamines and Metanephrines are Homovanillic acid (HVA) and Vanillylmandelic acid (VMA). Dopamine and Catecholamines are produced in elevated concentrations by the tumour cells of patients with pheochromocytoma. These patients often show hypertension, anxiety, pallor and trembling. Dopamine and Catecholamines and also produced by neuroblastoma cells but usually not in concentrations enough to produce symptoms. The urinary concentrations of Catecholamines and Metanephrines are important in the differential diagnosis of hypertension, for the evaluation of congestive cardiac insufficiency, coronary heart disease, diabetes mellitus, arteriosclerosis, acute asthma and others. In order to evaluate patients with autonomic stimulation (hypertension, anxiety, pallor, trembling, etc) or with pheochomocytoma the best clinical strategy is the HPLC-ECD measurement of urinary Catecholamines (hormones), Metanephrines (their metabolites) and HVA and VMA (the final metabolism products) :
Clinical Strategy using HPLC-ECD method
