TNM stage
Description
I131 Decreased risk of death
I131 Decreased risk of recurrence
May facilitate initial staging and follow-up
RAI usually recommended
T1a
≤1 cm, intrathyroidal, microscopic multifocal
No
No
Yes
No
T1b
1–2 cm intrathyroidal
No
Conflicting dataa
Yes
Selective usea
T2
>2–4 cm intrathyroidal
No
Conflicting dataa
Yes
Selective usea
T3
>4 cm
≤45 years old
No
Conflicting dataa
Yes
Yes
>45 years
Yes
Yes
Yes
Yes
Any size, any age, minimal extrathyroid extension
No
Inadequate dataa
Yes
Selective usea
T4
Any size with gross extrathyroidal extension
Yes
Yes
Yes
Yes
Nx, N0
No metastatic nodes documented
No
No
Yes
No
N1
≤45 years old
No
Conflicting dataa
Yes
Selective usea
>45 years old
Conflicting dataa
Conflicting dataa
Yes
Selective usea
M1
Distant metastasis
Yes
Yes
Yes
Yes
Preparation for Radioiodine Ablation or Therapy
Patient should adopt a low-iodine diet (see example in Table 27.2) for 2 weeks prior to RAI ablation or I131 or therapy and avoid sources of excess iodine such as:
Table 27.2
Example of low-iodine diet
Do eat
Try not to eat
Fresh and frozen fruit and vegetables
Seafood and fish
Fresh and frozen meats
Dairy product: cow’s/goat’s milk, cheese, ice cream, yoghurt, and butter
Rice, pasta, and potatoes
Egg yolks
Soft drinks, fruit juices, beer, wine, tea, coffee, and soya milk
Some cough mixtures and health foods (such as seaweed, kelp, cod liver oil, vitamins, and mineral supplements) contain iodine. If the label lists iodine, do not take the supplement while on this diet
Plain fats and oils (nondairy)
Avoid food from restaurants, fast-food chains, and takeaways
Olive oil spread
Fresh and home-made bread
The best way to make sure of the iodine content is to prepare your food from fresh ingredients yourself
Do not add any of the ingredients listed in the other box
Table salt with no added iodine may be used
1.
Iodine-based contrast for CT scanning (defer I131 for 2–3 months after iodine contrast)
2.
Amiodarone (defer I131 for 4–6 months after amiodarone withdrawal)
I131 uptake is thyroid-stimulating hormone (TSH) dependent.
I131 can be administered within 3–4 weeks of thyroidectomy if RAI ablation is planned well in advance and no thyroid hormone replacement is required in the interim period to allow TSH to rise.
If the period between thyroidectomy and RAI ablation is longer, patients should stop liothyronine (T3) for 2 weeks or levothyroxine (T4) for 4 weeks before I131 ablation or therapy.
Human recombinant TSH (Thyrogen™) 0.9 mg given intramuscularly on two consecutive days prior to I131 administration may be used without thyroid hormone withdrawal (THW) to avoid hypothyroid symptoms.Related posts:
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