Metanephrines in pheochromocytoma diagnosis

A new technical poster from ESA Analytical describes and illustrates how HPLC with electrochemical array detection can be used for the measurement of free, unconjugated metanephrines (normetanephrine and metanephrine) in plasma to aid the diagnosis of pheochromocytoma.

Currently clinicians rely on clinical laboratories to provide reliable screening methods for these tumors, as they often are the underlying cause of a patient's hypertension.

Several assays have historically been used to fulfill this need.

However rarely have these assays, based upon urinary metanephrines, urinary vanillylmandelic acid (VMA) and plasma or urinary catecholamines, provided the desired specificity and sensitivity needed to consistently detect these tumors and not generate costly false positives.

The data provided within the poster demonstrates a new technique that provides a reliable method for the determination of free metanephrines and 3-methoxytyramine (3-MT) in plasma.

The new technique employs initial solid phase extraction followed by isocratic HPLC with coulometric electrochemical detection to deliver the sought after clinical assay advances.

The ESA CoulArray system, with its unique multi-channel electrochemical array, is the only detector with the dynamic range and low detection capabilities to permit simultaneous determinations in complex biological matrices. Coulometric oxidation/reduction is imperative as the oxidation channel alone exhibits many interfering peaks and baseline noise. The CoulArray detector was particularly well suited to this type of assay as its auto ranging capabilities meant that large peaks associated with high concentrations of interfering species did not saturate the detector thus eliminating the need for further sample re-extraction.

For a free copy of the new technical poster and further information on the CoulArray detector, contact ESA Analytical (links above).