Radioiodine

Radioiodine Uses, Dosage, Side Effects, Food Interaction and all others data.

Radioiodine (as Sodium iodide I-131) is a radioisotopic drug used for the treatment and palliation of thyroid malignancy. Iodine-131 is notable for causing mutation and death in cells that it penetrates, which is due to its mode of beta decay. As a result of beta decay, approximately 10% of its energy and radiation dose is via gamma radiation, while the other 90% (beta radiation) causes tissue damage without contributing to any ability to see or image the isotope. Low levels of beta radiation are also known for causing cancer as this dose is highly mutagenic. For this reason, less toxic iodine isotopes such as I-123 are more frequently used in nuclear imaging, while I-131 is reserved for its tissue destroying effects. Because the thyroid gland naturally takes up iodine from the body, therapeutic methods using radioisotopes can take advantage of this mechanism for localization of drug to the site of malignancy.

Therapeutic solutions of Sodium Iodide-131 are indicated for the treatment of hyperthyroidism and thyroid carcinomas that take up iodine. Palliative effects may be observed in patients with advanced thyroid malignancy if the metastatic lesions take up iodine. It is also indicated for use in performance of the radioactive iodide (RAI) uptake test to evaluate thyroid function.

The therapeutic effects of sodium iodide I-131 are a result of the ionizing radiation absorbed by the thyroidal tissue. Tissue damage is the result of direct insult to molecules by ionization and excitation and the consequent dissociation of those molecules. About 90% of local irradiation from sodium iodide I-131 is the result of beta radiation and 10% is the result of gamma radiation.

Radioiodine
Uses
Dosage
Side Effect
Precautions
Interactions
Uses during Pregnancy
Uses during Breastfeeding
Accute Overdose
Food Interaction
Half Life
Volume of Distribution
Clearance
Interaction With other Medicine
Contradiction
Storage

Trade Name	Radioiodine
Generic	Iodide I-131
Iodide I-131 Other Names	Iodide I-131, Iodide I-131 ion, Iodide-131, iodine I-131, Radioiodine
Type
Formula	I
Weight	Average: 130.9067 Monoisotopic: 130.906672748
Protein binding	Sodium Iodide I-131 is not protein bound.
Groups	Approved, Investigational
Therapeutic Class
Manufacturer
Available Country
Last Updated:	September 19, 2023 at 7:00 am

Uses

Radioiodine is a radioisotopic agent used for the treatment of hyperthyroidism and thyroid carcinomas that take up iodine.

Radioiodine is also used to associated treatment for these conditions: Hyperthyroidism, Metastatic Medullary Thyroid Cancer, Neoplasms, Thyroid, Thyroid Carcinoma

How Radioiodine works

Taken orally, sodium iodide I-131 is rapidly absorbed and distributed within the extracellular fluid of the body. The iodide is concentrated in the thyroid via the sodium/iodide symporter, and subsequently oxidized to iodine. The destruction of thyroidal tissue is achieved by the beta emission of sodium iodide I-131.

Toxicity

Adverse reactions that have been reported with doses of sodium iodide I-131 used in the treatment of benign disease include sialadenitis, chest pain, tachycardia, iododerma, itching skin, rash, hives, hypothyroidism, hyperthyroidism, thyrotoxic crisis, hypoparathyroidism, and local swelling. Adverse reactions that have been reported with doses of sodium iodide I-131 used in the treatment of malignant disease include radiation sickness, bone marrow depression, anemia, leucopenia, thrombocytopenia, blood dyscrasia, leukemia, solid cancers, lacrimal gland dysfunction, salivary gland dysfunction, congenital hypothyroidism, chromosomal abnormalities, cerebral edema, radiation pneumonitis, and pulmonary fibrosis.

Food Interaction

Drink plenty of fluids.
Limit iodine intake. Consume a low iodine diet for two weeks before the administration of sodium Radioiodine.
Take on an empty stomach. Avoid eating for 2 hours before and after administering iodide I-131.

Elimination Route

After oral administration, sodium iodide I-131 is absorbed rapidly from the upper gastrointestinal tract (90% in 60 minutes). Following absorption, the iodide is primarily distributed within the extra-cellular fluid of the body. It is trapped by the thyroid. The thyroid uptake of iodide is usually increased in hyperthyroidism and in goiter with impaired hormone synthesis, decreased in hypothyroidism, and normal to decreased in hypothyroidism receiving iodine. It should be noted that the uptake of radioactive iodide is a function of stable iodide concentration in the serum and the functional state of the thyroid.

Half Life

Iodine I-131 decays by beta emission and associated gamma emission with a physical half-life of 8.04 days.

Elimination Route

Sodium Radioiodine is excreted by the kidneys. The normal range of urinary excretion is 37 to 75 % of the administered dose, varying with the thyroid and renal function of the patient.