I-131 Radioiodine Therapy (10 mCi) for Hyperthyroidism

As one of the proven and most effective treatments for certain types of hyperthyroidism such as Graves' disease, toxic multinodular goitre, and solitary hyperfunctioning nodules, I-131 Radioiodine Therapy (Radioiodine, 10 mCi) is an effective method. This treatment is effective because the thyroid naturally absorbs the iodine to treat the hyperthyroidism. 

At Molecular Diagnostics and Therapy, Dr. Nikunj Jain, Co-Founder and HOD – Nuclear Medicine, provides expert evaluation and personalised radioiodine treatment planning for patients with hyperthyroidism undergoing I-131 therapy. 

10 millicuries (mCi) of I-131 are given orally and are considered to be a low-dose treatment. Depending on the patient's status and radiation safety guidelines, this procedure is normally done in an outpatient setting. A 10 mCi dose can be administered, but the decision to use it is based upon the clinical appraisal of the person and on the nature of their thyroid condition.

Radioiodine therapy is not a novel procedure but has been successfully used for a long time in appropriate patients who have hyperthyroidism. This is also not invasive, painless, and provides long-term control of hyperthyroidism; in fact, patients who experience recurrent hyperthyroidism symptoms or who cannot control their condition with anti-thyroid drugs can benefit from this treatment.

What is I-131 Radioiodine Therapy for Hyperthyroidism?

Radioiodine therapy with I-131 is based on the fact that the thyroid gland naturally takes up iodine. I-131 is taken up by the thyroid cells and emits beta radiation, damaging the overactive thyroid cells that make too much thyroid hormone.

Radioiodine (I-131) therapy is a safe, potent, permanent cure that can sometimes be used to control hyperthyroidism for a long time. It takes time to affect overactive thyroid tissue, which is different than surgery or extended treatment with anti-thyroid drugs. This alleviates hyperthyroid symptoms and decreases the amount of antithyroid drugs required for chronic therapy. In other circumstances, however, hypothyroidism can develop following treatment and the patient may need to take thyroid replacement drugs for life.

Indications for I-131 Therapy (10 mCi)

Some patients may require 10mCi depending on the cause of the hyperthyroidism, size of the thyroid, level of uptake of the thyroid, clinical condition of the patient, and the protocol of the specialist treating the patient. Problems that I-131 can help treat are:

Graves’ Disease

A disorder in which the body produces too much thyroid hormone because the antibodies activate the thyroid.

Toxic Multinodular Goitre

There are some thyroid nodules that can secrete extra thyroid hormone independently of others.

Solitary Hyperfunctioning Nodule (Toxic Adenoma)

A single thyroid nodule that secretes too much thyroid hormone and can inhibit normal thyroid activity in the rest of the thyroid.

Recurrent Hyperthyroidism

When hyperthyroidism recurs after taking medicine or having surgery to correct it.

How Does the Treatment Work?

Oral Administration

The treatment comes in one dose, typically as a capsule or liquid. Depending on the person involved and radiation safety rules, 10 mCi is sometimes given on an outpatient basis.

Targeted Action

Radioiodine is taken up by thyroid cells. Overactive thyroid tissue slowly dies down over many weeks or months due to the beta radiation emitted.

Gradual Reduction in Thyroid Function

When the thyroid tissue overactivity decreases, so does the level of thyroid hormones. Others may have a return to normal thyroid hormone function, or it can remain permanently hypothyroid and be treated with thyroid hormone replacement pills, such as levothyroxine.

Preparation for I-131 Radioiodine Therapy

Preparation for the treatment is important to ensure that it happens safely and effectively.

Discontinuation of Anti-Thyroid Medications

Medications that patients may be advised to stop include:

• Carbimazole

• Methimazole

• Propylthiouracil

The timing of discontinuation varies depending on the medication, the patient's condition, and the treating doctor's instructions. Patients should stop or restart these medicines only as advised by their doctor.

Low-Iodine Diet

A low-iodine diet may be advised in selected cases, depending on the treating specialist's protocol. If recommended, the doctor or nuclear medicine team will provide specific dietary instructions.

Blood Tests and Thyroid Evaluation

Baseline tests may include:

• Thyroid Function Tests (TSH, T3, T4)

• Thyroid uptake scan, when required

• Complete blood count (CBC), when clinically indicated

• Liver and kidney function tests, when required

These tests help determine whether the patient is a suitable candidate for treatment and assist in treatment planning.

Post-Treatment Instructions

Follow the radiation safety guidelines provided by the nuclear medicine team after taking the capsule:

• Maintain an appropriate distance from children and pregnant women for the period advised by your doctor.

• Maintain distance from family members where necessary.

• Sleep separately for the period advised by your doctor.

• Avoid sharing utensils and personal items for the period advised by your doctor.

• Flush the toilet twice after use, if advised.

• Drink plenty of fluids, unless medically restricted, to help eliminate radioiodine from the body.

• Take anti-thyroid drugs only when instructed by your doctor.

What to Expect After the Therapy

The effects of radioiodine treatment are gradual, and most patients do not experience immediate changes. Over the next several weeks to months:

• Symptoms such as palpitations, tremors, anxiety, and weight loss may progressively improve.

• Thyroid function tests will be performed regularly to monitor the response to treatment.

• Some patients may develop hypothyroidism and require long-term or lifelong thyroid hormone replacement.

• Hyperthyroidism can often be managed with one dose; however, some patients may require a second dose.

Benefits of I-131 Therapy (10 mCi)

• Long-term or definitive treatment option for hyperthyroidism.

• Minimally invasive and non-surgical treatment.

• May reduce reliance on long-term anti-thyroid medication.

• High treatment success rate, particularly in Graves' disease and toxic nodules.

• Minimal discomfort and a low risk of serious side effects.

• Often performed as an outpatient treatment.

Risks and Side Effects

Most patients tolerate the treatment well, but possible side effects and risks may include:

• Hypothyroidism, which is common and can be treated with thyroid hormone replacement medication.

• Neck discomfort or swelling.

• Sore throat in some people.

• Temporary worsening of hyperthyroid symptoms in some patients.

• Worsening of thyroid eye disease in some patients with Graves' disease.

• Pregnant and breastfeeding women should not receive this treatment.

Your doctor will discuss any potential risks and ensure that appropriate precautions are taken.

Who Should Not Receive I-131 Therapy?

Contraindications to the therapy include:

• Pregnant women

• Breastfeeding mothers

Patients who have moderate to severe thyroid eye disease and are being monitored by a physician should only be treated with radioiodine under careful medical supervision. Preventive treatment with steroids may be considered in selected cases. Patients should inform their physician of any recent iodine exposure (such as a CT scan with contrast), as radioiodine uptake may be affected, which could influence treatment planning.

Follow-Up and Monitoring

Follow-up should be performed regularly. Monitoring generally involves:

• Thyroid function tests at regular intervals after treatment, especially during the first several months.

• Assessment for symptoms and signs of hypothyroidism.

• Initiation of levothyroxine when clinically indicated.

• Long-term follow-up to monitor and maintain appropriate thyroid hormone levels.

Conclusion

Radioiodine Therapy with 10 mCi of I-131 is a simple, effective, and proven long-term therapy for Graves' disease, and in the case of Toxic multinodular or goitrous Iodine-131 is a reliable and safe therapy. Selectively eliminates hyperactive thyroid tissue and helps to control overproduction of thyroid hormone, reduce symptoms, and prevent long-term consequences of untreated hyperthyroidism.

Radioiodine therapy is a successful and effective treatment, with an excellent success rate and low side effects that are proven for hyperthyroidism. Patients will be able to maintain control of their hyperthyroidism for an extended period of time if they follow radiation safety measures and consult their physician regularly. At Molecular Diagnostics and Therapy, Dr. Nikunj Jain and the nuclear medicine team provide comprehensive care, personalised treatment planning, and follow-up throughout the patient's radioiodine therapy journey.