Factors Interfering with Thyroid Uptake of Radioiodine, and Recommended Minimal Withdrawal Time Before Radioiodine Therapy
| Compound | Withdrawal time |
| Thyroid-related medications | |
| Antithyroid drugs* | 3–7 d to 2–3 wk |
| Perchlorate | 1 wk |
| Iodinated drugs or substances | |
| Amiodarone | 3–6 mo |
| Intravenous contrast agents† | 2–4 wk |
| Iodine-containing preparations | 4 wk |
| Lugol solution or SSKI | 4–6 wk |
| Kelp or seaweed | 2–4 wk |
| Oil-based contrast agents‡ | 3–6 mo |
↵* Methimazole, carbimazole, and propylthiouracil: longer withdrawal for methimazole, shorter for propylthiouracil.
↵† Currently used nonionic contrast agents undergo fast renal clearance, thus possibly requiring shorter withdrawal times.
↵‡ Rarely used in current clinical practice.
SSKI = supersaturated potassium iodide solution.