Treatment of Graves’ Disease When Methimazole Has Not Achieved Euthyroidism
In Graves’ disease, initial management targets normalisation of thyroid hormone levels. When first-line antithyroid drug therapy with Methimazole (MMI) does not achieve the intended biochemical response, a structured next-line protocol is indicated.
Why This Protocol Is Indicated
The previous line — Methimazole (MMI) — aimed to achieve biochemical euthyroidism: normalisation of serum free T4 and total or free T3, reassessed at 2–4 week intervals. When these targets are not reached, escalation to this next-line approach is appropriate.
Next-Line Approach (Partial Overview)
This protocol employs radioactive iodine (RAI) therapy — a targeted thyroid intervention distinct from antithyroid drug therapy — with specific additional provisions for patients who have active thyroid eye involvement. The complete regimen, clinical criteria, and adjunctive considerations are available in the full protocol.
Clinical Goal
Rendering the patient hypothyroid over a period of six weeks to six months.
References
- The goal of RAI treatment in GD is to administer sufficient activity to render the patient hypothyroid.
- This can be accomplished with the use of a fixed dose or calculating the activity based on goiter size and RAI uptake.
- In order to achieve hypothyroidism, activity of greater than 150 μCi/g (5.55 MBq/g) should be administered.
- RAI is a β radiation emitter with a long physical half-life of just over 8 days which is rapidly concentrated by the thyroid after oral ingestion.
- Patients with active mild TED are candidates for oral glucocorticoid therapy (0.3–0.5 mg of prednisone per kg of body mass per day, started 1–3 days after RAI administration, tapered over three months).
- The β particle has a range in tissue of approximately 2 mm and induces DNA damage and eventual thyroid cell death, rendering most patients with GD hypothyroid over a period of six weeks to six months.
DOI: 10.1016/j.ecl.2021.12.004.
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