Drug-Related Factors That May Affect RBC Labeling with 99mTc
| Drug-related factor | Effect on RBC labeling with 99mTc |
|---|---|
| Drug interactions | |
| Heparin | Competes with RBCs for Sn2+ ion |
| Chemotherapy | Disrupts RBC cell membrane |
| Digoxin or calcium channel blocker | Interferes with uptake of Sn2+ |
| Metronidazole or ranitidine | Alters outer cell membrane |
| Iodinated contrast material less than 24 h before scintigraphy | Mechanism unknown |
| Quinidine or dipyridamole | Blocks transmembrane transport |
| Propranolol | Increases dissociation |
| Circulating antibodies: prior transfusion, transplantation | Alters outer cell membrane |
| Low hematocrit value | Reduces 99mTc outside RBCs |
| Abnormal hemoglobin (thalassemia, sickle-cell disease) | Alters structure of hemoglobin |
| Renal failure, recent stroke, acute myocardial infarction, diabetes mellitus | Mechanism(s) unknown |