Performance characteristics of an LC-MS/MS method for the determination of plasma metanephrines

Catecholamines and their metabolites, metanephrines, are produced excessively in pheochromocytoma tumors of the chromaffin cells. Increased concentrations of these compounds produce symptoms and allow for clinical evaluation of disease. Historically, screening for such tumors by determination of catecholamines and metabolites in urine yielded false negative results in individuals with a genetic predisposition for the disease and those with paroxysmal hypertension. Analysis of metanephrines in plasma, however, is of decisive diagnostic importance. This test exhibits high sensitivity and specificity for the analytes produced by tumors.

Plasma proteins are removed by solid phase extraction. Chromatographic isolation of the analytes and stable isotope internal standards is achieved by elution on a HILIC column connected to a UPLC MS/MS system. Metanephrines are measured using multiple reaction monitoring with an electrospray source operating in positive ion mode.

The method was validated for linearity, limit of quantification, accuracy, and precision. The method was accurate and correlated well to a comparison HPLC method. Potential interferences were evaluated.

Results from this LC-MS/MS assay enable clinical diagnosis of pheochromocytoma and aid in monitoring treatment outcomes.