Causes of Reduced RBC Labeling Efficiency
| Cause | Drug or process |
| Oxidation of stannous ion | Hydralazine |
| Heparin | |
| Methyldopa | |
| Decreased hematocrit | |
| Inadequate reduction of 99mTc | Excess stannous chloride |
| Insufficient stannous chloride | |
| Formation of RBC antibodies | Methyldopa |
| Penicillin | |
| Quinidine | |
| Immune disorders | |
| Leukemia and lymphoma | |
| Complex formation with 99mTc | Dextrose |
| Decreased RBC labeling | Prazosin |
| Digoxin | |
| Propranolol | |
| Mechanism unknown | Doxorubicin |
| Iodinated contrast |
(Adapted from (4)).