Increased catecholamine excretion during normotensive phase in paroxysmal type of pheochromocytoma.

Seven patients with paroxysmal type of pheochromocytoma were studied from the diagnostic point of view, because diagnosis of this type of pheochromocytoma may be difficult if the patient was seen during attackfree period. Comparison of catecholamine levels in timed urine specimens before and after histamine test was made. A clear increase of catecholamine excretion was found after histamine provocation, however, significantly high concentration of the amine was observed in all normotensive control urine specimens. Histamine test was hazardous and tyramine test was less valuable as a provocation test in patient with paroxysmal type. From these findings, we concluded that no more provocation test was necessary for the screening purpose. Catecholamine assay using 1 hour urine specimen could be valuable for establishing the diagnosis of pheochromocytoma, because of its accuracy and safety.