Radioactive iodine for thyroid carcinoma is given by
## **Core Concept**
Radioactive iodine, specifically **Iodine-131 (¹³¹I)**, is used in the treatment and management of **thyroid carcinoma**, particularly for **differentiated thyroid cancers** such as papillary and follicular thyroid carcinoma. This treatment leverages the thyroid gland's natural uptake of iodine to target and destroy thyroid tissue, including cancer cells.
## **Why the Correct Answer is Right**
The correct answer, **. ¹³¹I (Radioiodine)**, is used for thyroid carcinoma because it emits **beta particles** and **gamma rays**. The beta particles have a localized effect, damaging the DNA of thyroid cancer cells and ultimately leading to cell death. The gamma rays allow for **imaging and tracking** of the distribution of ¹³¹I in the body. This targeted approach minimizes damage to non-thyroid tissues.
## **Why Each Wrong Option is Incorrect**
- **Option A:** This option is incorrect because while **oral administration** is a common route for radioactive iodine, the specificity of the route (oral) does not inherently make it incorrect without context. However, the focus here is on the form or type of radioactive iodine rather than the administration route.
- **Option B:** This option might refer to a different radioactive isotope or a different compound not specifically used for thyroid carcinoma treatment. **Iodine-123 (¹²³I)** is used for diagnostic imaging due to its shorter half-life and lower radiation dose but is not typically used for therapy.
- **Option C:** This could potentially refer to another compound or isotope not primarily used for therapeutic purposes in thyroid carcinoma.
## **Clinical Pearl / High-Yield Fact**
A key point to remember is that **radioactive iodine therapy** is particularly effective for **differentiated thyroid cancers** (papillary and follicular) that take up iodine. Patients often need to **discontinue thyroid hormone replacement therapy** before treatment to elevate TSH levels, enhancing iodine uptake by thyroid cells.
## **Correct Answer:** . ¹³¹I (Radioiodine)