The Use of a Double-Isotope Derivative Plasma Assay for Noradrenaline and Adrenaline in the Diagnosis and Localisation of Phaeochromocytoma

A sensitive double-isotope derivative plasma assay has been used to measure total plasma catecholamines, noradrenaline (NA) and adrenaline (A) in patients with phaeochromocytoma and essential hypertension. Plasma samples containing as little as 0.5 ng of NA or A could be measured accurately. All nine patients with phaeochromocytoma had significant elevations in either total plasma catecholamines (p<.02) or plasma NA (p<.001). Separation of NA and A with less than 0.3% cross contamination was carried out by thin layer chromatography. This represents a substantial improvement over other methods of assay and raises the possibility that differential plasma assay of NA and A will be of value in diagnosing extra-adrenal tumours. Differential plasma NA and A levels were measured in five patients with phaeochromocytoma. Four of these had elevated NA and A levels and were later found to have adrenal tumours. The other patient had a mediastinal tumour and no measurable plasma adrenaline.