I-131 metaiodobenzylguanidine uptake in a parathyroid adenoma

We describe a patient with multicentric small bowel carcinoids, severe hypertension, primary hyperparathyroidism, and multiple parathyroid adenomas. Intense uptake of I-131 metaiodobenzylguanidine (MIBG) occurred in a parathyroid adenoma. There was no biochemical evidence of catecholamine secretion by the tumor but elevated serum levels of parathyroid hormone were demonstrated. We suspect that occasional parathyroid adenomas, like other APUDomas, may give false positive results when MIBG imaging is used to search for pheochromocytomas. This observation supports the inclusion of the parathyroid chief cells in the amine precursor uptake and decarboxylation (APUD) cell system.