Altered biodistribution of Tc-99m HMDP on bone scintigraphy from recent intravenous iron therapy

A 68-year-old woman with a history of gastrointestinal arteriovenous (AV) malformations was admitted with profound anemia (hemoglobin 4.5 gm/dl). She received three units of packed red blood cells during the next 2 days and 1 g of intravenous iron on the third day. Bone imaging was also performed on day 3 because of isolated elevation of the serum alkaline phosphatase. The bone scan demonstrated Paget's disease in the pelvis as the cause of the abnormal laboratory value. In addition, it demonstrated prominent blood pool activity as a result of altered biodistribution of the Tc-99m diphosphonate bone agent caused by circulating iron dextran complex.