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

In the context of insulinoma, which is a tumor that secretes insulin, the radiopharmaceutical that may cause hypoglycemia is 111In-pentetreotide. This substance is a somatostatin analog that binds to somatostatin receptors, which are often overexpressed in neuroendocrine tumors, including insulinomas. When 111In-pentetreotide is administered, it can lead to an increased uptake of somatostatin in the insulinoma cells, potentially stimulating insulin secretion and causing hypoglycemia in patients who are already sensitive to insulin secretion or have existing hyperinsulinism.

The other radiopharmaceuticals listed do not have this effect. 99mTc-sestamibi is primarily used for myocardial perfusion imaging and assessing parathyroid gland function. 67Ga-citrate is used in certain types of infections and malignancies but does not have an effect on blood sugar levels. 18F-FDG is a glucose analog used in PET imaging to evaluate metabolic activity in tumors but does not induce hypoglycemia by itself. Thus, 111In-pentetreotide stands out for its potential effect on insulin secretion related to insulinoma.