Iron Polymaltose Infusion Effects on Bone Scintigraphy and Remodeling

A 73-year-old woman with metastatic breast cancer and known widespread skeletal metastases was referred for bone scintigraphy. Delayed images acquired at 2 and 5 hours postinjection of 30 mCi (1089 MBq) Tc-99m-HDP demonstrated markedly reduced bony uptake, markedly increased renal activity, and significantly increased soft tissue accumulation. By contrast, appropriate skeletal uptake of Tc-99m-HDP was seen in prior bone scans. The patient had been treated for iron deficiency anemia with an infusion of 1 g of iron polymaltose approximately 22 hours before injection of Tc-99m-HDP. This phenomenon may be due to transient reduced bone resorption with increased FGF23 release secondary to IV iron supplementation.