A new method for the simultaneous analysis of free and sulfoconjugated normetanephrine, metanephrine, and 3-methoxytyramine in human urine by HPLC with electrochemical detection.
A sensitive and specific assay for free and sulfoconjugated normetanephrine, metanephrine, and 3-methoxytyramine was achieved by tetraphenylboron complexing and by high-performance liquid chromatography with electrochemical detection. Sulfoconjugated metabolites were hydrolyzed by sulfatase. Complexing the 3-O-methylated catecholamines with tetraphenylboron followed by their extraction in either and reextraction in dilute hydrochloric acid succeeded in partially purifying the sample without the use of a prepacked column. Detection by electrochemical technique additionally eliminates unoxidable components in the urine. The relatively high sensitivity of this method permits measurement of metabolite concentrations as low as 10 ng/ml, allowing for the first time the determination of free 3-O-methylated catecholamines in human urine. Hydrolysis by sulfatase specifically identifies the form of the conjugated metabolite. The mean total (free plus sulfoconjugated) values of normetanephrine, metanephrine, and 3-methoxytyramine obtained from 25 normal volunteers were 214, 102, and 227 micrograms/day, respectively. Values were greatly increased in patients with pheochromocytoma. The degree of sulfoconjugation varied, and each individual metabolite was highest with normetanephrine (86%). This method is sensitive, rapid, simple, and can be easily standardized for clinical investigation of pheochromocytoma.
D000310:Adrenal Gland Neoplasms / Q000175:diagnosis; D000328:Adult; D002851:Chromatography, High Pressure Liquid; D004298:Dopamine / Q000031:analogs & derivatives* / Q000652:urine; D004837:Epinephrine / Q000031:analogs & derivatives*; D005260:Female; D006801:Humans; D008297:Male; D008676:Metanephrine / Q000652:urine*; D008875:Middle Aged; D009647:Normetanephrine / Q000652:urine*; D010673:Pheochromocytoma / Q000175:diagnosis; D013429:Sulfatases / Q000378:metabolism
D009647:Normetanephrine; D008676:Metanephrine; D013429:Sulfatases; C001746:3-methoxytyramine; D004298:Dopamine; D004837:Epinephrine