Causes of Interference with Erythrocyte Radiolabeling, Leading to Free 99mTc-Pertechnetate (9–15)
| Cause | Mechanism of disrupted radiolabeling |
| Methyldopa | Oxidation of stannous ion; decrease in reduction |
| Hydralazine | Oxidation of stannous ion; decrease in reduction |
| Quinine | Possible antibody to red blood cells |
| Doxorubicin | Lowered labeling efficiency in proportion to concentration of drug |
| Iodinated contrast medium | Decrease in stannous reduction; alteration of 99mTc binding |
| Chocolate | Unknown |
| Tobacco | Oxidation of stannous ion, possible damage to red blood cell plasma membrane or possible chelating action on stannous or pertechnetate ions (mechanism relates to reactive oxygen species present) |
| Heparin | Formation of complexes with 99mTc-pertechnetate in presence of stannous ion, causing renal excretion |
| Too much or too little stannous ion | Alteration of 99mTc-pertechnetate reduction |
| Recent blood transfusion | Unknown |
| Sickled red blood cells | Impaired labeling due to abnormal hemoglobin structure |