methimazole and Pheochromocytoma

Topics: alpha-Methyltyrosine; Antihypertensive Agents; Antithyroid Agents; Catecholamines; Enzyme Inhibitors; Female; Fluid Therapy; Graves Disease; Humans; Hypertension; Hypotension; Methimazole; Middle Aged; Pheochromocytoma; Time Factors

We describe a patient with right adrenal tumor detected incidentally. The tumor was diagnosed as pheochromocytoma by endocrinological and radiological studies, and was removed surgically. Graves' disease, which had been in remission for more than two decades after discontinuation of antithyroid drug treatment, relapsed during preoperative evaluation of pheochromocytoma when the patient was treated with alpha- and beta1-adrenergic antagonists. Administration of methimazole resulted in a rapid improvement of thyroid function and the patient remained euthyroid on small doses of methimazole. This case may suggest possible involvement of excessive catecholamine secretion and beta2-adrenergic receptor activation by pheochromocytoma in the relapse of Graves' disease.

Topics: Adrenal Gland Neoplasms; Adrenergic alpha-Antagonists; Adrenergic beta-Antagonists; Antithyroid Agents; Dose-Response Relationship, Drug; Doxazosin; Female; Graves Disease; Humans; Hypertension; Incidental Findings; Methimazole; Middle Aged; Pheochromocytoma; Propanolamines; Recurrence

The human Sipple syndrome associates a thyroid-C-cell tumor and a pheochromocytoma. A treatment with the antithyroid drug thiamazole allows obtaining experimentally a similar syndrome in rat. Present paper seeks to analyse changes which happened in the medullary zone of adrenal glands before and during the development of the tumors. During the treatment by thiamazole both adrenal cortex and medulla were atrophied. After the treatment was stopped, the weight of the gland increased, as compared with its previous state, and this was chiefly due to the hyperplasia of medullary cells, from which pheochromocytomas originate. The initial atrophy of adrenal gland depends on the thiamazole-induced hyperthyroidism, but the mechanism of the medullary hyperplasia subsequent to the treatment ending is unknown. It results probably from a secondary hyperthyroidism.

Topics: Adrenal Gland Neoplasms; Adrenal Medulla; Animals; Male; Methimazole; Neoplasms, Experimental; Pheochromocytoma; Rats; Rats, Inbred Strains; Syndrome; Thyroid Neoplasms

Sipple syndrome, associating a C cells or parafollicular thyroid tumor and a pheochromocytoma of the medullary part of adrenal gland, can be experimentally induced with the use of an antithyroid drug, the thiamazole, in the rat. The treatment is applied here either between 3 and 11 months, or between 6 and 14 months of age. Tumors appear a long time after the treatment is stopped. Hypotheses are proposed to explain this phenomenon.

Topics: Adrenal Gland Neoplasms; Animals; Male; Methimazole; Neoplasms, Experimental; Pheochromocytoma; Rats; Syndrome; Thyroid Neoplasms