Radioactive iodine · Thyroid care
Iodine-131 Therapy for Hyperthyroidism in Malaysia
Radioactive iodine (I-131) is an established treatment for selected patients with an overactive thyroid, including Graves’ disease and toxic thyroid nodules. The treatment uses the thyroid’s natural ability to absorb iodine.
How radioactive iodine works
After I-131 is swallowed as a capsule or liquid, it enters the bloodstream and is concentrated by thyroid cells. Its beta radiation gradually reduces the activity of overfunctioning thyroid tissue while limiting exposure to most other organs.
The response is not immediate. Symptoms and thyroid hormone levels generally improve over weeks to months, so continued clinical and biochemical follow-up is important.
Before treatment
- Confirm the cause of hyperthyroidism and review thyroid function tests.
- Tell the team about pregnancy, breastfeeding and plans for conception.
- Review antithyroid medicines and iodine-containing medicines or recent contrast exposure.
- Follow only the preparation instructions provided by the treating nuclear medicine unit.
- Plan temporary radiation-safety precautions for family members and the public.
Results and long-term follow-up
Dr Zool Hilmi’s 2013 Master of Medicine thesis examined outcomes of I-131 therapy for hyperthyroidism at Hospital Kuala Lumpur. The work reflects the importance of local outcome monitoring alongside established international practice.
Hypothyroidism may develop after treatment and is managed with levothyroxine. Some patients require further assessment or an additional treatment depending on the underlying disease and response.
Side effects and precautions
- Temporary neck discomfort or thyroid tenderness.
- A temporary change in thyroid symptoms or hormone levels.
- Development of hypothyroidism during follow-up.
- Specific distancing, hygiene and sleeping arrangements for a limited period, according to the administered activity and local rules.
Frequently asked questions
Questions patients often ask
What does Iodine-131 do?
The thyroid naturally absorbs iodine. I-131 is taken up by overactive thyroid tissue and emits beta radiation that gradually reduces thyroid activity.
How quickly does it work?
Improvement develops gradually and the full effect may take several weeks to months. Thyroid blood tests are required during follow-up.
Can hypothyroidism occur?
Yes. An underactive thyroid is an expected long-term outcome in many patients, particularly after treatment for Graves’ disease, and is treated with thyroid hormone replacement.
Who should not receive radioactive iodine?
Radioactive iodine is contraindicated during pregnancy and breastfeeding. Individual suitability, medicines and radiation precautions must be discussed with the treating team.
Clinical references
This patient information was prepared with reference to authoritative clinical and professional sources.