Radioactive iodine therapy, often referred to as RAI or I-131 therapy, is a specialized medical treatment employed to address various thyroid disorders, most notably hyperthyroidism and certain types of thyroid cancer. This therapy harnesses the unique characteristics of iodine and the physiology of the thyroid gland, providing a targeted approach that minimizes impact on the rest of the body.
What Is Radioactive Iodine Therapy?
Radioactive iodine therapy utilizes iodine-131, a radioactive isotope, to selectively destroy thyroid tissue. The thyroid gland, located at the base of the neck, uses iodine to produce essential hormones that regulate metabolism. Because thyroid cells have a natural affinity for iodine, administering radioactive iodine allows for precise targeting: the gland absorbs the isotope, which then emits radiation that destroys overactive or malignant cells.
Clinical Applications
Hyperthyroidism
One of the most common uses of radioactive iodine therapy is to treat hyperthyroidism, a condition characterized by excessive production of thyroid hormones. Graves’ disease, toxic multinodular goiter, and solitary toxic adenoma are among the primary causes. In these cases, RAI is used to reduce thyroid function by ablating (destroying) overactive cells.
Thyroid Cancer
Radioactive iodine therapy is a cornerstone in managing differentiated thyroid cancer—including papillary and follicular carcinoma—after surgical removal of the thyroid (thyroidectomy). It is used to eliminate residual thyroid tissue or microscopic cancerous cells, thereby reducing recurrence risk.
Preparation for Therapy
Successful treatment with RAI requires careful preparation. Patients may be asked to:
- Cease Thyroid Hormone Medications: Stopping medications like levothyroxine temporarily increases thyroid-stimulating hormone (TSH), heightening iodine uptake by any remaining thyroid cells.
- Adopt a Low-Iodine Diet: Consuming foods low in iodine for 1–2 weeks ensures that thyroid cells are “hungry” for iodine, maximizing absorption of the radioactive dose.
- Assess Pregnancy and Breastfeeding: RAI is contraindicated in pregnant or breastfeeding individuals due to risk of harm to the fetus or infant.
Before therapy, additional imaging and blood tests are often performed to assess thyroid function and evaluate the extent of disease.
The Treatment Process
The actual administration of radioactive iodine is generally straightforward. The isotope is given orally, either as a capsule or liquid. The dose varies according to the condition being treated, patient size, and clinical goals. Most patients receive therapy in an outpatient setting, although hospitalization may be required for higher doses.
Once ingested, I-131 is rapidly absorbed into the bloodstream and taken up by thyroid cells. The radioactive decay of iodine-131 releases beta and gamma radiation, selectively destroying targeted thyroid tissues.
Safety and Precautions
While radioactive iodine therapy is generally safe, it does involve exposure to radiation, necessitating certain precautions:
- Isolation: Patients may need to avoid close contact with others—especially children and pregnant individuals—for several days after therapy, as small amounts of radiation are excreted in saliva, urine, and sweat.
- Personal Hygiene: Frequent handwashing, flushing the toilet twice, and using disposable utensils may be recommended to limit radiation exposure to others.
- Travel Restrictions: Temporary limitations on travel, especially by air, may apply due to radiation detection protocols at airports.
Healthcare providers will give clear, detailed instructions to ensure safety during and after treatment.
Benefits of Radioactive Iodine Therapy
RAI therapy offers several advantages:
- Targeted Action: The treatment specifically targets thyroid cells, sparing most healthy tissues.
- Non-invasive: RAI is administered orally, eliminating the need for surgical intervention in many cases.
- High Success Rate: For hyperthyroidism, the majority of patients achieve remission; for thyroid cancer, RAI can substantially lower recurrence risk.
- Minimal Side Effects: Most patients tolerate the therapy well, with few serious adverse effects.
Potential Side Effects and Risks
Despite its favorable profile, RAI therapy is not devoid of risks. Some common side effects include:
- Temporary Neck Tenderness: Mild pain or swelling at the site of the thyroid gland may occur.
- Nausea and Taste Changes: The therapy can cause nausea or a metallic taste in the mouth, usually transient.
- Dry Mouth or Salivary Gland Damage: Rarely, inflammation or reduced function of the salivary glands develops, leading to dry mouth.
- Hypothyroidism: As the thyroid tissue is destroyed, many patients eventually develop hypothyroidism, requiring lifelong thyroid hormone replacement.
- Fertility Concerns: Temporary changes in fertility may occur, especially in higher doses.
Long-term risks are considered minimal, but a small increase in the risk of certain cancers and blood disorders has been noted in some studies, especially after repeated high-dose treatments.
Follow-Up and Long-Term Management
Post-treatment, patients are closely monitored through blood tests and physical exams to assess thyroid hormone levels and ensure complete ablation of the targeted tissue. For those who develop hypothyroidism, thyroid hormone replacement (e.g., levothyroxine) becomes a lifelong necessity.
In thyroid cancer patients, ongoing surveillance includes imaging and measurement of thyroglobulin levels. Most individuals resume normal activities within a few days to weeks following RAI.
Special Considerations
Radioactive iodine is not suitable for everyone. Contraindications include pregnancy, breastfeeding, certain types of thyroid cancer (like medullary or anaplastic), and individuals with severe uncontrolled comorbidities. Children may receive RAI for certain indications, but the risks and benefits must be weighed more carefully.
Nursing Care of Patients Undergoing Radioactive Iodine Therapy
While RAI is generally safe and effective, it requires specialized nursing care to ensure patient safety, minimize exposure risks, and promote healing.
Pre-Therapy Nursing Responsibilities
Patient Assessment
- Conduct a thorough assessment of the patient’s medical history, current medications, allergies, and prior thyroid treatments.
- Evaluate the patient’s understanding of the procedure, expectations, and potential side effects.
- Assess for pregnancy status in women of childbearing age, as RAI is contraindicated during pregnancy and breastfeeding.
- Review renal function, as impaired excretion can increase radiation exposure to non-thyroid tissues.
Patient Preparation and Education
- Educate the patient about the procedure, including its purpose, process, and expected outcomes. Use clear, non-technical language.
- Discuss dietary restrictions, typically a low-iodine diet for 1-2 weeks prior to therapy to enhance RAI uptake by the thyroid gland.
- Advise discontinuation of certain medications (e.g., antithyroid drugs, iodine-containing supplements) as directed by the physician.
- Instruct on the need for isolation during and after treatment to minimize radiation exposure to others.
- Prepare the patient emotionally for temporary separation from family, especially young children and pregnant individuals.
- Ensure informed consent is obtained after providing comprehensive information and answering questions.
During Therapy
Administration of Radioactive Iodine
- Verify patient identity, prescribed dose, and method of administration (usually oral capsule or solution).
- Observe for immediate adverse reactions, such as nausea, vomiting, or hypersensitivity.
- Ensure the patient remains in a designated isolation room, equipped with radiation safety signage and restricted access.
- Employ personal protective equipment (PPE) such as gloves and gowns when handling materials potentially contaminated with radioactive iodine.
Radiation Safety Measures
- Limit time spent in proximity to the patient, maintain safe distance, and use shielding as appropriate.
- Monitor radiation levels in the patient’s room using dosimeters and survey meters, documenting findings regularly.
- Instruct the patient to avoid contact with visitors and minimize interaction with staff except when necessary.
- Ensure proper disposal of radioactive waste (e.g., tissues, vomitus, urine) according to institutional and regulatory guidelines.
- Advise the patient to flush the toilet twice after use and maintain good personal hygiene to reduce contamination.
- Schedule meals and medication delivery in a manner that minimizes staff exposure.
Post-Therapy Nursing Care
Monitoring and Assessment
- Monitor vital signs and observe for delayed side effects such as sore throat, dry mouth, altered taste, or salivary gland inflammation.
- Assess for signs of hypothyroidism or thyroid hormone imbalance, which may occur weeks to months after therapy.
- Watch for radiation-induced complications, including bone marrow suppression and secondary malignancies.
Patient Instructions and Support
- Provide written and verbal instructions for home care, emphasizing continued radiation precautions for a specified period (usually 1–2 weeks).
- Advise the patient to sleep alone, avoid close contact (especially with children and pregnant people), and maintain a distance of at least one meter from others.
- Recommend frequent handwashing, use of separate utensils, towels, and laundry, and avoidance of public places.
- Instruct on symptoms that require immediate medical attention, such as severe swelling, pain, fever, or persistent vomiting.
- Educate about possible delayed effects and the importance of follow-up appointments for thyroid function monitoring.
Psychosocial Care
- Address feelings of anxiety, isolation, or fear related to radioactive treatment and enforced separation.
- Encourage communication with family and support networks via telephone or virtual means.
- Provide reassurance regarding radiation safety, emphasizing that precautions are temporary and necessary for everyone’s well-being.
- Facilitate access to counseling services if needed.
Special Considerations
Pediatric Patients
- Additional psychological support may be needed for children, who may struggle with isolation and fear.
- Ensure age-appropriate education and involve family in care planning.
Pregnant and Breastfeeding Patients
- RAI is contraindicated during pregnancy and breastfeeding; screen all patients for pregnancy prior to therapy.
- If breastfeeding, advise discontinuation well in advance of treatment as radioactive iodine can concentrate in breast tissue and be excreted in milk.
Patients with Renal Impairment
- Close monitoring for retention of radioactive iodine and increased risk of systemic exposure is essential.
- Collaborate with nephrology for dose adjustments and additional safety measures.
Documentation and Legal Considerations
- Meticulously document all aspects of patient care, assessments, education, and radiation safety measures.
- Maintain records of radiation levels, waste disposal, and staff exposure.
- Ensure compliance with institutional protocols and local/national regulatory policies regarding radioactive material handling.
Discharge Planning and Follow-Up
- Confirm that the patient understands all home safety precautions before discharge.
- Arrange for follow-up appointments for thyroid function tests and assessment of treatment efficacy and side effects.
- Provide contact information for immediate support and resources.
REFERENCES
- American Cancer Society. Radioactive Iodine (Radioiodine) Therapy for Thyroid Cancer. https://www.cancer.org/cancer/types/thyroid-cancer/treating/radioactive-iodine.html. Last revised 2/28/2023.
- American Thyroid Association. Radioactive Iodine. http://www.thyroid.org/wp-content/uploads/patients/brochures/Radioactive_iodine_brochure.pdf.
- Madu NM, Skinner C, Oyibo SO. Cure Rates After a Single Dose of Radioactive Iodine to Treat Hyperthyroidism: The Fixed-Dose Regimen. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9400920/. Cureus. 2022 Aug;14(8):e28316.
- Cynthia DeMarco, Radioactive iodine therapy: 9 things to know, Published December 03, 2021, https://www.mdanderson.org/cancerwise/radioactive-iodine-therapy–9-things-to-know.h00-159466368.html
- National Library of Medicine (U.S.). Radioiodine Therapy. https://medlineplus.gov/ency/article/007702.htm Last reviewed 11/3/2022.
- Padda IS, Nguyen M. Radioactive Iodine Therapy. https://www.ncbi.nlm.nih.gov/books/NBK557741/ 2023 Jun 3. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan.
- RadiologyInfo.org. Radioactive Iodine (I-131) Therapy for Hyperthyroidism. https://www.radiologyinfo.org/en/info/radioiodine. Last reviewed 11/1/2022.
- Society of Nuclear Medicine & Molecular Imaging (U.S.). Fact Sheet: Guidelines for Patients Receiving Radioiodine I-131 Treatment. https://www.snmmi.org/AboutSNMMI/Content.aspx?ItemNumber=5609
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