I-131 Radioiodine Therapy – 30 mCi

I-131 Radioiodine Therapy – 30 mCi is a form of nuclear medicine surgery to remove the remainder of thyroid tissue in patients with other thyroid conditions treated with thyroid surgery (e.g., papillary, follicular thyroid cancer). At Molecular Diagnostics and Therapy, Dr. Nikunj Jain, Co-Founder and HOD – Nuclear Medicine, provides expert guidance for patient selection and radioiodine treatment planning. Even though the thyroid has been removed, there may be small amounts of thyroid tissue or small cancer cells remaining.

Radioiodine given in a low dose kills the rest of the tissue, lowers the chances of cancer returning, and makes follow-up easier as well. The thyroid is typically able to take up the iodine in the blood and make thyroid hormones. Similarly, radioiodine also acts in this way, with the iodine being taken up by the remaining cells of the thyroid. The cells become radioactive and absorb radiation, causing their destruction, but not the destruction of most other tissues. The low dose treatment is a 30 mCi dose and is typically used when small amounts of thyroid tissue are removed in a patient who is at low risk. Alternatively, it is usually given without hospitalisation.

What is Radioiodine Therapy?

Radioiodine therapy is a procedure in which a small amount of radioactive iodine is used to kill any remaining thyroid tissue or any cancer cells. This therapy assists with the following:

• Ablate residual thyroid following thyroidectomy.

• Destroy minute cancer cells that may still be present.

• Enhance follow-up tests, including thyroglobulin blood tests.

• Enhance the usefulness of scans in the future.

• Minimize the likelihood of recurrence of cancer.

A 30 mCi dose is generally recommended for patients with low-risk thyroid cancer, especially if imaging does not show that the lymph nodes and distant spread of the thyroid cancer are considered low risk.

Why is the 30 mCi Dose Used?

A dose of 30 mCi is given to certain patients to destroy remnants of the thyroid gland. May be recommended if:

• The patient has a small amount of residual thyroid tissue following near-complete thyroidectomy.

• It is a low-risk cancer and shows no evidence of disease on scans.

• The physician desires that the patient be prepared to undergo extensive surveillance using thyroglobulin.

• There is very limited thyroid tissue remaining.

• The physician believes that the low dosage suffices.

A 30 mCi dose works well, like high doses, to remove the tissue, but keeps radiation and side effects low.

Preparation Before I-131 Therapy (30 mCi)

The therapy should be properly prepared. Raising the TSH level and following a low-iodine diet are two important steps.

1. Elevation of TSH (Thyroid Stimulating Hormone)

For radioiodine to be effectively absorbed by residual thyroid cells, TSH levels should typically be above 30 mIU/L. TSH elevation stimulates thyroid tissue to absorb iodine more efficiently. Two methods are used to achieve this.

Thyroid Hormone Withdrawal

Patients stop taking thyroid hormone replacement medication (such as levothyroxine) for 3–4 weeks before therapy. This causes TSH levels to rise naturally due to temporary hypothyroidism. Possible symptoms during withdrawal may include:

• Fatigue

• Weight gain

• Cold intolerance

• Constipation

• Low mood

• Menstrual irregularities

These symptoms are temporary and resolve once hormone therapy is restarted.

Recombinant Human TSH (rhTSH – Thyrogen®)

Another option is rhTSH injections, given over two consecutive days before therapy. Benefits include:

• Patients can continue taking thyroid hormone medication.

• Avoids symptoms of hypothyroidism.

• More convenient for elderly patients or those with other medical conditions.

Your doctor decides the most suitable preparation method.

2. Low-Iodine Diet

A low-iodine diet for 1–2 weeks before treatment helps reduce iodine levels in the body, improving the uptake of radioactive iodine by the remaining thyroid cells.

Foods to Avoid

• Iodized salt or sea salt

• Dairy products (milk, cheese, yogurt)

• Seafood (fish, shrimp, seaweed)

• Egg yolks

• Soy products

• Processed foods containing iodized salt

• Foods with red food dye (may contain iodine)

Foods Allowed

• Fresh fruits and vegetables

• Egg whites

• Non-iodized salt

• Fresh, unprocessed meat and poultry

• Plain rice, pasta, and homemade bread without iodized salt

How is I-131 Radioiodine Therapy (30 mCi) Administered?

The therapy is usually given orally in the form of a capsule or liquid solution. Key points include:

• Patients may need to fast for about 4 hours before and after the dose.

• The treatment is generally performed on an outpatient basis.

• A short observation period may be required after administration.

After receiving the dose, the radioactive iodine travels through the bloodstream and is absorbed by the remaining thyroid cells.

Post-Therapy Safety Instructions

Although the radiation dose is relatively low, some precautions are recommended for 3–5 days after therapy to reduce radiation exposure to others. Patients may be advised to:

• Maintain distance from children and pregnant women.

• Sleep separately from others for a few days.

• Use a separate bathroom if possible.

• Flush the toilet twice after use.

• Avoid kissing or close physical contact.

• Avoid sharing utensils or food.

• Wash your hands frequently and maintain good hygiene.

• Drink plenty of fluids to help eliminate radioactive iodine from the body.

Your nuclear medicine team provides detailed written instructions specific to your situation.

Follow-Up After 30 mCi Therapy

A post-therapy whole-body scan may be performed 3–7 days after treatment to:

• Confirm iodine uptake in residual thyroid tissue.

• Detect any unexpected areas of iodine uptake.

• Evaluate the effectiveness of the ablation.

Long-term follow-up may include:

• Blood tests for serum thyroglobulin levels.

• Neck ultrasound.

• Periodic diagnostic scans if needed.

• Adjustment of thyroid hormone replacement dosage.

Benefits of Low-Dose I-131 Therapy (30 mCi)

• Effective for low-risk differentiated thyroid cancer.

• Targeted treatment with minimal effect on other tissues.

• Lower radiation exposure compared to higher doses.

• Usually does not require hospital admission.

• Helps improve the accuracy of long-term monitoring.

• Generally well tolerated by patients.

Possible Side Effects

Side effects are usually mild and temporary, especially with a low dose such as 30 mCi. Some patients may experience:

• Dry mouth

• Altered taste sensation

• Mild nausea

• Fatigue

• Neck discomfort or swelling

• Temporary menstrual changes

These symptoms typically resolve within a short time.

Conclusion

I-131 Radioiodine Therapy – 30 mCi is a surgery alternative that is safe and effective therapy for selected patients with low-risk differentiated thyroid cancer following thyroidectomy. Treatment locates and eliminates any remaining thyroid tissue, which makes keeping track of thyroid cancer easier in the long run and decreases the risk of recurrence.

The treatment has minimal side effects and excellent results if the patient is well prepared, including elevated TSH and low iodine levels. It is important for patients to educate themselves with their endocrinologist or their nuclear medicine physician to see if this therapy suits them and is appropriate for their situation. At Molecular Diagnostics and Therapy, Dr. Nikunj Jain and the nuclear medicine team provide personalised care and guidance throughout every stage of radioiodine therapy.

Instructions

• Follow the low-iodine diet advised by your doctor or nuclear medicine specialist, usually for 1–2 weeks before treatment.

• Your TSH level may need to be adequately elevated before therapy. Follow your doctor’s instructions regarding thyroid hormone withdrawal or recombinant human TSH (rhTSH) injections.

• Inform your doctor about all medications, supplements, vitamins, herbal products, and recent iodine-containing medicines or contrast studies, as these may affect radioiodine uptake.

• Do not stop or restart thyroid hormone medication unless specifically advised by your doctor.

• You may be instructed to fast for a few hours before and after the treatment. Follow the preparation instructions provided by your nuclear medicine team.

• Inform your doctor if you are pregnant, think you may be pregnant, or are breastfeeding. Radioiodine therapy is not given during pregnancy, and breastfeeding must be stopped according to medical advice before treatment.

• Carry your previous thyroid reports, including thyroid function tests, thyroglobulin reports, neck ultrasound, biopsy reports, surgical records, and previous scans, if available.

• Arrive at the centre 10–15 minutes before your scheduled appointment for registration and preparation.

निर्देश

• उपचार से पहले डॉक्टर या न्यूक्लियर मेडिसिन विशेषज्ञ द्वारा बताई गई लो-आयोडीन डाइट का पालन करें। आमतौर पर यह डाइट उपचार से 1–2 सप्ताह पहले शुरू की जाती है।

• उपचार से पहले आपका TSH स्तर पर्याप्त रूप से बढ़ा हुआ होना आवश्यक हो सकता है। थायरॉइड हार्मोन की दवा बंद करने या recombinant human TSH (rhTSH) इंजेक्शन के संबंध में डॉक्टर के निर्देशों का पालन करें।

• आप जो भी दवाइयाँ, विटामिन, सप्लीमेंट, हर्बल उत्पाद या आयोडीन युक्त दवाइयाँ ले रहे हैं, उनकी जानकारी डॉक्टर को अवश्य दें। हाल ही में कराई गई आयोडीन कॉन्ट्रास्ट वाली जांच की जानकारी भी दें, क्योंकि इससे रेडियोआयोडीन के अवशोषण पर प्रभाव पड़ सकता है।

• डॉक्टर की सलाह के बिना थायरॉइड हार्मोन की दवा बंद या दोबारा शुरू न करें।

• उपचार से पहले और बाद में कुछ घंटों के लिए फास्टिंग करने की सलाह दी जा सकती है। अपनी न्यूक्लियर मेडिसिन टीम द्वारा दिए गए निर्देशों का पालन करें।

• यदि आप गर्भवती हैं, गर्भवती होने की संभावना है या स्तनपान करा रही हैं, तो डॉक्टर को अवश्य बताएं। गर्भावस्था के दौरान रेडियोआयोडीन थेरेपी नहीं दी जाती और उपचार से पहले स्तनपान डॉक्टर की सलाह के अनुसार बंद करना आवश्यक होता है।

• अपनी पुरानी थायरॉइड जांच रिपोर्ट, जैसे थायरॉइड फंक्शन टेस्ट, थायरोग्लोबुलिन रिपोर्ट, नेक अल्ट्रासाउंड, बायोप्सी रिपोर्ट, सर्जरी रिकॉर्ड और पुरानी स्कैन रिपोर्ट, यदि उपलब्ध हों, साथ लेकर आएं।

• पंजीकरण और तैयारी के लिए निर्धारित समय से 10–15 मिनट पहले केंद्र पर पहुंचें।

Procedure

• Before treatment, the nuclear medicine team reviews your medical history, reports, preparation status, and relevant laboratory results.

• The prescribed dose of I-131 Radioiodine is administered orally as a capsule or liquid.

• The radioactive iodine is absorbed into the bloodstream and taken up mainly by any remaining thyroid tissue or iodine-avid thyroid cancer cells.

• The treatment itself is quick and painless. A short observation period may be required after administration.

• You will receive personalised radiation-safety instructions regarding contact with family members, sleeping arrangements, hygiene, toilet use, and other precautions after treatment.

• Drink adequate fluids as advised to help remove the remaining radioactive iodine from the body.

• A post-therapy whole-body scan may be scheduled several days after treatment, depending on your doctor’s recommendation.

• Follow-up may include thyroglobulin blood tests, thyroid function tests, neck ultrasound, and other investigations, as advised by your doctor.