High epinephrine content in the adrenal tumors from Sipple's syndrome

Percent of epinephrine content to total catecholamine is low in pheochromocytomas irrespective of unilateral or bilateral adrenal origin when they have no medullary carcinoma of the thyroid. However, epinephrine content higher than norepinephrine has been noted in the adrenal tumors from the patients with Sipple's syndrome. Although an exact reason for this remained unknown, our data could suggest that the adrenal tumors in Sipple's syndrome are primarily different from other types of pheochromocytoma, and thorough examinations for detecting the thyroid carcinoma should be necessary when the adrenal tumor is rich in epinephrine.