Identification and quantification of N-methylepinephrine in human urine.

N-Methylepinephrine was analysed in human urine using a high-performance liquid chromatographic catecholamine assay. The identity of the compound was confirmed by gas chromatography-mass spectrometry. The excretion of N-methylepinephrine is slightly less than that of epinephrine: excretion values were in the range 2-65 nmol per 24 h (0.4-13 micrograms per 24 h) in 150 hypertensive patients. In addition to increased epinephrine excretion, increased urinary excretion of N-methylepinephrine was found in three out of five patients with histologically proven pheochromocytoma.