In the case of insulinoma, which radiopharmaceutical may cause hypoglycemia?

In the case of insulinoma, the correct choice is In111 pentetreotide. This radiopharmaceutical is a somatostatin analogue, which binds to somatostatin receptors that are often overexpressed in neuroendocrine tumors, including insulinoma. When In111 pentetreotide is administered, it can lead to increased insulin secretion from the tumor cells, resulting in hypoglycemia. The stimulation of insulin release occurs due to the interaction of the radiolabeled compound with the tumor, which, being a source of excess insulin, can lead to lower blood glucose levels.

On the other hand, the other radiopharmaceuticals listed do not have this effect. In111 white blood cells are used primarily for detecting infections and assessing inflammatory conditions. 99mTc sestamibi is mainly utilized in myocardial perfusion imaging and parathyroid gland localization, with no significant involvement in insulin regulation. Similarly, 67Ga citrate is typically used for oncology and infection imaging but does not influence blood sugar levels in the context of insulinoma. Thus, the unique mechanism of In111 pentetreotide makes it the only option that may contribute to hypoglycemia in this scenario.