[Elevated level of methylated catecholamine derivatives is a pathognomic laboratory sign of pheochromocytoma]

The levels of the methylated catecholamine derivatives (MCD) metanephrine and normetanephrine were measured in 46 patients operated on. The patients were divided into 2 groups: 1) 24 patients in whom chromaffinoma was histologically detected; their age varied from 9 to 75 years (mean 37.8 years); 2) 22 patients who had undergone adrenal cortical tumors or retroperitoneal tumors of extraadrenal genesis; their age ranged from 11 to 67 years (mean 44.3 years). In this group of patients, a histological study revealed aldosteromas in 7 cases, hormonally inactive adrenal cortical adenomas in 6, adrenocortical carcinoma in 5, corticosteroma in 1, adrenal lymphosarcoma in 1, adrenolypoma in 1, and renal cancer in 1. In all the patients from Group 1, there was an increase of one MCD index for instance of less than 110% of the upper normal range. The average excess of MCD levels over the upper normal range is 456% for metanephrine and 574% for normetanephrine. No increase in the level of daily MCD excretion was found in 21 out of the 22 Group 2 patients with nonchromaffin adrenal and retroperitoneal tumors. In this group, 1 patient with histologically verified mixed-cell adenocarcinoma of the adrenal cortex was observed to have a daily metanephrlne excretion increase by 17% above the upper reference range. Thus, the sensitivity of the method was 100%; its specificity was 95.5%. The lower confidence diagnostic interval for the values of daily MCD excretion was 714 ng/day for metanephrlne and 1500 ng/day for normetanephrine. The procedure for determining free MCD in plasma has a high sensitivity and specificity and may be once used as a screening for the symptomatic nature of disease in patients with arterial hypertension.