Metanephrine-d₃is intended for use as an internal standard for the quantification of metanephrine by GC- or LC-MS. Metanephrine is an inactive metabolite of epinephrine .¹It is formed from epinephrine by catechol-O-methyl transferase (COMT).²Urinary and plasma levels of metanephrine are increased in patients with pheochromocytoma, an adrenal medullary neuroendocrine tumor.^3,4

1.Bilezikian, J.P., Dornfeld, A.M., and Gammon, D.E.Structure-binding-activity analysis of beta-adrenergic amines—I. Binding to the beta receptor and activation of adenylate cyclaseBiochem. Pharmacol.27(10)1445-1454(1978) 2.Kopin, I.J., Axelrod, J., and Gordon, E.The metabolic fate of H3-epinephrine and C14-metanephrine in the ratJ. Biol. Chem.236(7)2109-2136(1961) 3.Wolthers, B.G., Kema, I.P., Volmer, M., et al.Evaluation of urinary metanephrine and normetanephrine enzyme immunoassay (ELISA) kits by comparison with isotope dilution mass spectrometryClin. Chem.43(1)114-120(1997) 4.Goldstein, D.S., Eisenhofer, G., and Kopin, I.J.Sources and significance of plasma levels of catechols and their metabolites in humansJ. Pharm. Exp. Ther.305(3)800-811(2003)