Guidance times for withholding substances that may interfere with NIS-mediated thyroid radio-pharmaceutical uptake prior to imaging
| Interfering substance | Recommended time to withhold prior to imaging |
|---|---|
| Anti-thyroid drugs | Pertechnetate imaging Can be continued 123I or 131I 2–4 days |
| Thyroxine (T4) therapy | 4–6 weeks |
| Triiodothyronine (T3) therapy | 2 weeks |
| Exogenous iodine (eg water-soluble iodinated contrast) | 6–8 weeks |
| Amiodarone | Greater than 6 months |
Adapted from Balon et al.8