Question

After exposure to radioactive fallout containing \({ }^{131} \mathrm{I}\), which agent could be administered to prevent destruction of thyroid tissue? (A) liothyronine (B) methimazole (C) propranolol (D) potassium iodide (E) levothyroxine

Short answer

Potassium iodide (D) is the correct agent to prevent thyroid damage from radioactive iodine exposure.

Step-by-step solution

Understand the Problem

The problem is asking for a substance that can be used to protect the thyroid gland from damage after exposure to radioactive iodine, specifically \( ^{131} \mathrm{I} \). We need to find an agent that prevents the thyroid from absorbing this radioactive material.

Recall the Purpose of Each Agent

- Liothyronine and levothyroxine are thyroid hormones used to treat hypothyroidism, not for preventing radioactive iodine damage. - Methimazole is a medication that inhibits thyroid hormone production, which might not be directly protective in this context. - Propranolol is a beta-blocker, used primarily to manage symptoms of hyperthyroidism but not to block iodine uptake. - Potassium iodide is known to block thyroid uptake of radioactive iodine by saturating the gland with non-radioactive iodine.

Analyze the Options

The goal is to saturate the thyroid gland with stable iodine so that it does not uptake the radioactive iodine (\( { }^{131} \mathrm{I} \)). Among the options given, potassium iodide (D) is the agent known to serve this protective purpose.

Conclusion

Potassium iodide is effective in preventing the uptake of radioactive iodine by the thyroid by providing a large amount of non-radioactive iodine, thus preventing thyroid tissue damage.

Key concepts

Radioactive iodine protection

When exposed to a radioactive environment, particularly one involving radioactive iodine such as \( ^{131} \mathrm{I} \), it becomes crucial to protect key tissues from this dangerous substance. Radioactive iodine has the ability to be absorbed by the thyroid gland, posing a significant risk of thyroid damage. To mitigate this risk, certain methods and substances are employed to shield the body from harm.

The protection against radioactive iodine primarily involves preventing its uptake. This is achieved by saturating the thyroid gland with stable, non-radioactive iodine.

• The thyroid gland can only absorb a limited amount of iodine at a time.
• By filling it with stable iodine, the gland becomes less capable of absorbing the radioactive version.

Using substances like potassium iodide provides this saturation effect, thereby limiting the destructive potential of radioactive iodine on the thyroid.

Thyroid gland protection

The thyroid gland is a critical component of the endocrine system, regulating various metabolic processes. It is highly sensitive to iodine levels, both stable and radioactive. Protecting this gland from radioactive iodine is necessary to prevent potential adverse health effects.

The thyroid gland uses iodine to produce essential hormones like thyroxine \((T_4)\) and triiodothyronine \((T_3)\). This makes it a prime target during radioactive events involving iodine. Effective thyroid gland protection involves ensuring that only stable iodine is absorbed.

• A saturated thyroid will not significantly uptake new iodine, radioactive or not.
• This protective mechanism is relatively simple but highly effective.

Therefore, understanding the function of the thyroid gland and its dependency on iodine is key to implementing successful protection strategies in radioactive scenarios.

Potassium iodide function

Potassium iodide (KI) plays a crucial role in protecting the thyroid gland from radioactive iodine exposure. The function of potassium iodide in this context is straightforward yet highly effective.

When administered appropriately, potassium iodide floods the thyroid with a safe form of iodine.

• This process is called "thyroid blocking" and significantly reduces the uptake of radioactive iodine.
• It is most effective when taken shortly before or just after exposure to radioactive iodine.

The efficiency of potassium iodide in protecting the thyroid stems from timing and dosage. It doesn't remove radioactive iodine already absorbed but prevents more from entering the gland.

Proper education on the use of potassium iodide, including when and how to take it, is essential for maximizing its protective benefits against radioactive iodine exposure.