I-131 Radioiodine Therapy – 200 mCi

I-131 Radioiodine Therapy, 200 mCi is an intensive dose treatment with radioiodine, used to treat a selected group of people who have differentiated thyroid cancer (Papillary Thyroid Cancer and Follicular Thyroid Cancer). In case when the thyroid cancer has recurred, metastasized, or is resistant to treatments, or is hard to examine.

In the case of the removal of the thyroid gland, there is a chance that thyroid tissue or thyroid cancer remains in the body. In Radioiodine therapy, radioactive iodine (I-131) is administered, which is absorbed by the cells of the thyroid, therefore concentrating the radiation on the thyroid cells and not harming the normal surrounding tissues from the radiation. In the case that the doctor treating the patient thinks that the patient has progressed disease or disease has metastasized, he may recommend this higher dose treatment of I-131.

At Molecular Diagnostics and Therapy, Dr. Nikunj Jain, Co-Founder and HOD – Nuclear Medicine, provides expert evaluation and personalised treatment planning for patients requiring high-dose I-131 Radioiodine Therapy for advanced thyroid cancer.

Understanding I-131 and Its Therapeutic Role

Radioactive iodine (I-131) is radioactive and produces beta radiation, which is damaging to particular thyroid tissue and thyroid cancer cells. After thyroid surgery, I-131 treatment can be used to treat your thyroid for the following reasons:

• Eliminate any hormones remaining in the thyroid.

• Do away with very small thyroid cancer cells.

• Treat metastatic thyroid cancers that take up the radioactive iodine.

• Minimize the chance of the build-up and reappearance of disease.

• Enhance long-term monitoring with serum thyroglobulin and diagnostic imaging.
  
  

The 200 mCi dose is administered with a high dosage of treatment and is administered under the strict care of professionals.

Why is the 200 mCi Dose Used?

Selected clinical cases may warrant a 200 mCi dose, such as:

• Persistent or recurrent differentiated thyroid cancer.

• Thyroid cancer with distant metastases, such as to the lungs or bones.

• Extensive residual thyroid tissue following surgery.

• Elevated thyroglobulin levels suggesting persistent disease.

• Selected high-risk thyroid cancer patients requiring higher-dose therapy.

Patients with thyroid cancer who were deemed to be high risk and who needed treatment with a greater amount of radioactive iodine.

Preparation Before I-131 Radioiodine Therapy – 200 mCi

The correct preparation enhances the uptake of radioactive iodine and the efficacy of the treatment.

1. Elevation of TSH (Thyroid-Stimulating Hormone)

If possible, a pretreatment TSH level of over 30 mIU/L should be obtained so that the cells left in the thyroid absorb the radioactive iodine and stimulate the gland. There are two typical methods for preparing these into your body for this therapy:

Thyroid Hormone Withdrawal

Therapy is discontinued for 3–4 weeks before patients begin taking thyroid hormone medication (like levothyroxine). This leads to a temporary hypothyroidism, which causes TSH levels to go up. Possible symptoms include:

• Fatigue

• Weight gain

• Cold intolerance

• Constipation

• Low mood

• Slower heart rate

These symptoms usually improve once thyroid hormone therapy is restarted.

Recombinant Human TSH (Thyrogen®)

In some patients, medications known as recombinant human TSH (rTSH) may be given as two daily injections before treatment. Benefits include:

• Patients can continue taking thyroid hormone medication.

• Avoids symptoms of hypothyroidism.

• Suitable for selected patients who are unable to undergo hormone withdrawal.

Your doctor determines the most appropriate preparation method.

2. Low-Iodine Diet

Patients are often recommended to take a low-iodine diet for 1-2 weeks before therapy. This decreases the body's iodine reserves and increases radioactive iodine uptake.

Foods to Avoid

• Iodized salt and sea salt

• Dairy products

• Seafood and seaweed

• Egg yolks

• Soy products

• Foods containing red food dye

• Multivitamins containing iodine

Foods Allowed

• Fresh fruits and vegetables

• Egg whites

• Plain rice and pasta

• Non-iodized salt

• Fresh meat and poultry without additives

How is I-131 Radioiodine Therapy (200 mCi) Administered?

The therapy is administered orally as a capsule or, less commonly, as a liquid. Important points include:

• Patients are usually asked to fast for about 4 hours before and after treatment.

• A 200 mCi dose generally requires hospital admission in a radiation isolation room, depending on local regulations.

• Patients remain under medical supervision until radiation levels are considered safe for discharge.

The radioactive iodine enters the bloodstream and is selectively absorbed by thyroid tissue and thyroid cancer cells.

Radiation Safety Guidelines

Strict radiation safety precautions are needed after treatment because this is a high therapeutic dose. Treatment may involve recommendations to:

• Avoid close contact with children and pregnant women.

• Remain isolated for the period advised by the treating team.

• Sleep separately from others.

• Use separate towels and eating utensils where possible.

• Flush the toilet twice after each use.

• Wash hands thoroughly after using the toilet.

• Drink plenty of fluids to help eliminate radioactive iodine.

Before discharge, the nuclear medicine team gives detailed written instructions.

What Happens After the Therapy?

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

• As a general rule, a whole-body scan is done 3-7 days after therapy to:

• Ensure uptake into thyroid tissue or metastatic lesions.

• Identify more areas of radioactive iodine uptake.

• Assess the effectiveness of treatment.

Long-term follow-up may include:

• Tshb levels and blood thyroglobulin.

• TSH and thyroid hormone level check.

• Neck ultrasound.

• Further radiography as indicated/required.

Benefits of I-131 Radioiodine Therapy – 200 mCi

• Usually, very effective treatment is available for high-risk patients who have thyroid cancer.

• Spares most normal tissues while destroying thyroid tissue.

• Aids in the treatment of cancer that has spread to other parts of the body from the thyroid.

• Minimizes the chances of progression and recurrence of disease.

• Enhances medium and long-term monitoring of disease.

• May diminish the need for more treatment in appropriate patients.

• Possible Side Effects

Possible Side Effects

Any side effects temporary and may be more severe at higher doses. Patients might have these symptoms:

• Nausea

• Fatigue

• Any pain or swelling in the neck area.

• Dry mouth

• Altered taste sensation

• Salivary gland swelling

• Temporary menstrual irregularities
  
  

Sometimes, exposures are larger and cause a reduction in fertility or suppression of the marrow, or a secondary cancer may develop. These risks are discussed by the doctor who treats you before you have treatment.

Conclusion

A well-established and very effective treatment for selected patients with differentiated (papillary or follicular) thyroid cancer who have persistent, recurrent, or metastatic disease is I-131 radioiodine therapy (50 mCi to 200 mCi). It selectively eliminates the remaining thyroid tissue and iodine-avid cancer cells, resulting in better long-term control of the disease, and the risk of recurrence is decreased.

If their thyroid cancer is late stage and if they take preventive steps to ensure the safety of radiation, this can be a good treatment for them when used in tandem with follow-up check-ups if they have made proper preparations and taken the necessary measures to ensure the safety of radiation. To determine whether or not the patient needs the higher 200 mCi dose, the advice of the endocrinologist or nuclear medicine doctor should be sought. At Molecular Diagnostics and Therapy, Dr. Nikunj Jain and the nuclear medicine team provide comprehensive treatment planning, personalised care, and long-term follow-up for patients undergoing high-dose I-131 Radioiodine Therapy. 

Test Information

Fasting: 4 hours before therapy

Reporting: Not Applicable

Instructions

• Fast for 4 hours before your scheduled therapy, unless your doctor advises otherwise.

• Drink plenty of water before and after the treatment to help flush the radioactive iodine from your body.

• Inform your doctor about all medications, especially thyroid hormone replacement, anti-thyroid medicines, iodine-containing supplements, vitamins, or recent iodinated contrast studies.

• Follow a low-iodine diet for 1–2 weeks before therapy if instructed by your doctor.

• Your doctor may advise thyroid hormone withdrawal or recombinant human TSH (Thyrogen®) injections before treatment to improve radioactive iodine uptake.

• Women should inform their doctor if they are pregnant, planning pregnancy, or breastfeeding, as this treatment is contraindicated during pregnancy and breastfeeding.

• Carry your previous thyroid surgery records, pathology reports, thyroid scan reports, blood test results (including TSH and thyroglobulin), and your doctor's prescription.

• Arrive at the centre 30–60 minutes before your scheduled appointment for registration and pre-treatment assessment.

निर्देश

• उपचार से 4 घंटे पहले उपवास (फास्टिंग) रखें, जब तक डॉक्टर अन्य निर्देश न दें।

• उपचार से पहले और बाद में पर्याप्त मात्रा में पानी पिएँ, जिससे रेडियोआयोडीन शरीर से जल्दी बाहर निकल सके।

• यदि आप थायरॉयड की दवाएँ, एंटी-थायरॉयड दवाएँ, आयोडीन युक्त सप्लीमेंट, विटामिन ले रहे हैं या हाल ही में कॉन्ट्रास्ट सीटी स्कैन कराया है, तो इसकी जानकारी डॉक्टर को अवश्य दें।

• यदि डॉक्टर सलाह दें, तो उपचार से 1–2 सप्ताह पहले लो-आयोडीन डाइट का पालन करें।

• बेहतर परिणाम के लिए डॉक्टर थायरॉयड हार्मोन बंद करने या Thyrogen® इंजेक्शन की सलाह दे सकते हैं।

• यदि आप गर्भवती हैं, गर्भधारण की योजना बना रही हैं या स्तनपान करा रही हैं, तो उपचार से पहले डॉक्टर को अवश्य बताएं क्योंकि इस स्थिति में यह उपचार नहीं किया जाता।

• अपने साथ थायरॉयड सर्जरी की रिपोर्ट, बायोप्सी/पैथोलॉजी रिपोर्ट, थायरॉयड स्कैन, TSH एवं थायरोग्लोबुलिन की रिपोर्ट तथा डॉक्टर का प्रिस्क्रिप्शन लेकर आएँ।

• पंजीकरण और आवश्यक तैयारी के लिए निर्धारित समय से 30–60 मिनट पहले केंद्र पर पहुँचें।

Procedure

• Your nuclear medicine specialist reviews your medical history, thyroid surgery details, and recent blood test results before the therapy.

• The prescribed I-131 Radioiodine (200 mCi) dose is administered orally as a capsule or liquid.

• You may be observed briefly after receiving the dose, and hospital admission in a radiation isolation room is usually required for this high-dose therapy, depending on institutional and regulatory guidelines.

• The radioactive iodine is absorbed by any remaining thyroid tissue or iodine-avid thyroid cancer cells, where it delivers targeted radiation.

• Before discharge, you will receive detailed radiation safety instructions regarding contact with others, hygiene, diet, and follow-up.

• The therapy itself is painless, and administration usually takes only a few minutes, although the hospital stay depends on radiation safety requirements.