Radionucleotide Evaluation of GI Bleeding

  • Harjit SinghEmail author
  • Janet A Neutze


The radiopharmaceutical used in nuclear medicine to detect gastrointestinal bleeding is Technetium 99m-labeled autologous red blood cells (Tc-99m RBC). Labeling of red blood cells is possible because the radionuclide technetium 99m pertechnetate (TcO 4 ) freely crosses the red blood cell membrane via anion exchange. However, once TcO 4 is reduced, it can no longer pass through the red blood cell membrane. Therefore, it follows that if TcO 4 is allowed to cross the RBC membrane and subsequently reduced within the cell, Tc-99m will be trapped within the RBC. This is precisely how RBCs are labeled for a nuclear medicine GI bleeding study. The agent used to reduce TcO 4 is tin (Sn+2). The protocol involves pretreating red blood cells with tin followed by exposure to TcO 4 . The intracellular tin reduces the TcO 4 trapping it within the cell. The reduced technetium 99m binds to the beta chain of hemoglobin (see Fig. 36.1


Anion Exchange Duodenal Ulcer Beta Chain Proximal Small Bowel Nuclear Medicine Study 
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Copyright information

© Springer Science+Business Media, LLC 2012

Authors and Affiliations

  1. 1.Pennsylvania State College of MedicinePenn State Hershey Medical CenterHersheyUSA
  2. 2.Pennsylvania State College of MedicinePenn State Hershey Medical CenterHersheyUSA

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