Urinary Epinephrine and Norepinephrine Excretion in Patients with Medullary Thyroid Carcinoma and Their Relatives

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Abstract
Medullary thyroid carcinoma can arise as a component of multiple endocrine neoplasia (MEN) syndrome which includes adrenal pheochromocytoma. Familial medullary thyroid carcinoma with no association of other components of MEN syndrome is also reported. Epinephrine and norepinephrine excreted in 24 hour urine and/or randomly voided urine were measured for screening of pheochromocytoma in patients with medullary thyroid carcinoma of either the hereditary or sporadic type and in their relatives. Six patients with clinical symptoms and signs suggesting pheochromocytoma had a markedly increased epinephrine and epinephrine/norepinephrine (E/N) ratio and a less dominant increase of norepinephrine in 24 hour urine. The diagnosis of pheochromocytoma was proved later at surgery. Among 10 patients with hereditary medullary thyroid carcinoma without any clinical symptoms and signs for pheochromocytoma, 6 patients had increased epinephrine and E/N ratio and normal norepinephrine, and the remaining 4 had normal epinephrine, norepinephrine and E/N ratio in 24 hour urine. The six patients with increased epinephrine and E/N ratios were regarded as having latent adrenal medullary hyperfunction. The mean ages of the 6 patients with proved pheochromocytoma, the 6 with latent adrenal medullary hyperfunction and the 4 with normal urinary catecholamine fractions were 51.3, 42.5 and 28.5 years, respectively. At least one patient in each family with hereditary medullary thyroid carcinoma had proved pheochromocytoma or latent adrenal medullary hyperfunction, leaving no family with hereditary medullary thyroid carcinoma only. Urinary epinephrine, norepinephrine and E/N ratios in patients with sporadic medullary thyroid carcinoma and relatives of patients with medullary thyroid carcinoma were not higher than those in normal subjects. Measurements of epinephrine and norepinephrine in randomly voided urine are also a valuable and convenient method for the screening of pheochromocytoma in patients with medullary thyroid carcinoma and their relatives, because they gave results similar to those in 24 hour urine.

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