Endocrine Abstracts

Pheocromocytoma is a catecholamine-secreting tumor that arises from chromaffin cells of the adrenal medulla. In general, they are unilateral and the treatment of choise is complete surgical resection. Surgery and other medical procedures such as chemotherapy or radiotherapy may result in massive catecholamine release that can be fatal. Some form of preoperative pharmacologic preparation is indicated for all patients to control blood pressure, arrhytmia and promote intravascular volume expansion. Combined α and β-adrenergic blockade is the adopted approach by most centers. Until now, phenoxybenzamine has been the preferred α-adrenergic blocking agent. However, due to the its recent unavailability, we used other agent, a selective α1-adrenergic blocking agent – doxazosin. The authors report three different clinical cases in which doxazosin was used.

Case 1: A 58-year-old woman with a malignant pheocromocytoma with hepatic and vertebral ganglia metastatic lesions in whom bilateral adrenal resection had previously been made. She was now submitted to tumor irradiation with therapeutic doses of ¹³¹I-MIBG.

Case 2: A 65-year-old woman submitted to right adrenalectomy for a pheocromocytoma.

Case 3: A 36-year-old woman with MEN2A who had been previously submitted to bilateral adrenalectomy and radical thyroidectomy in another institution. She had a biochemical and imaging confirmed relapse of disease (left adrenal loca node, localized by ¹²³I-MIBG) and refused surgical management. She came for the first time to our department already pregnant – 26th week of gestation. Elective cesarean section was performed in the 38th week of gestation.

Doxazosin was a safe and effective alternative in these three cases. There is no great experience with this agent, specially during pregancy. Its more favorable side effect profile compared to fenoxybenzamine may be an advantange and will be reviewed in this presentation.