You need Iodine | Thyroid Function

Summary

In this biochemistry video, Medicosis explores the essential role of iodine in thyroid hormone production. He explains how iodine deficiency leads to hypothyroidism and goiter, highlighting the intricate process of thyroid hormone synthesis involving iodine and tyrosine. The video also covers the significance of iodized salt in preventing iodine deficiency and the potential consequences of iodine toxicity, such as thyroid ablation. Medicosis uses humor and relatable examples to explain the science behind thyroid function, making the complex topic of iodine metabolism accessible and engaging for viewers.

Takeaways

• 😀 Iodine and iodide are different forms of the same element, similar to chlorine and chloride, with iodide being the ion form.
• 😀 Iodine is a micronutrient essential for thyroid function and the production of thyroid hormones like T3 and T4.
• 😀 A goiter, or swelling of the neck, doesn't always indicate hyperthyroidism; it could result from iodine deficiency and hypothyroidism.
• 😀 Iodine deficiency can cause hypothyroidism, which leads to symptoms like bradycardia, constipation, weight gain, and dry skin.
• 😀 The thyroid gland requires iodine and tyrosine to produce thyroid hormones, with iodine playing a key role in oxidation, organification, and coupling.
• 😀 Thyroid hormone production occurs in the follicles of the thyroid gland, where iodide is trapped, oxidized to iodine, and incorporated into thyroglobulin.
• 😀 Excessive TSH from hypothyroidism stimulates the thyroid to grow in size, leading to goiter due to negative feedback from low thyroid hormones.
• 😀 Seafood, milk, and iodized salt are primary dietary sources of iodine, with iodized salt significantly reducing cases of hypothyroidism and goiter.
• 😀 Radioactive iodine can be used to treat thyroid cancer by ablation, but this can destroy the thyroid gland.
• 😀 Potassium iodide is used in the event of nuclear exposure to block radioactive iodine from entering the thyroid, though it can temporarily impair thyroid function.

Q & A

What is the difference between iodine and iodide?

Iodine and iodide are essentially the same, with the key difference being that iodide refers to the ionized form of iodine, similar to the difference between chlorine and chloride. Iodide is the form that enters the thyroid gland for hormone production.

What is a goiter, and why does it occur?

A goiter is the swelling of the thyroid gland, which can happen when the gland is overworked due to iodine deficiency. It occurs because of excessive stimulation by thyroid-stimulating hormone (TSH) from the pituitary, even though the thyroid gland cannot produce enough thyroid hormone due to a lack of iodine.

Is iodine a macronutrient or a micronutrient?

Iodine is a micronutrient, also referred to as a trace element, because the body requires it in very small amounts (less than 100 milligrams per day).

How does iodine enter the thyroid follicular cells?

Iodine enters thyroid follicular cells through a sodium-iodide symporter, a secondary active transport mechanism that works in conjunction with the sodium-potassium ATPase pump, which helps in trapping iodide inside the cells.

What is the role of iodine in thyroid hormone production?

Iodine is crucial for the synthesis of thyroid hormones. It combines with tyrosine (an amino acid) within the thyroid gland to form T3 (triiodothyronine) and T4 (thyroxine), the two primary thyroid hormones that regulate metabolism.

What happens to the thyroid when there is iodine deficiency?

Iodine deficiency leads to a decreased production of thyroid hormones, which triggers the hypothalamus and pituitary to release more TRH and TSH in an attempt to stimulate the thyroid. This results in thyroid enlargement (goiter) because of the excess TSH.

How does iodine deficiency affect metabolism?

Iodine deficiency causes hypothyroidism, which leads to a slowdown in metabolism. This can result in symptoms like bradycardia (slow heart rate), constipation, cold intolerance, coarse hair, dry skin, weight gain, and depression.

What is the importance of iodized salt?

Iodized salt was introduced to prevent iodine deficiency and related diseases such as hypothyroidism and goiter. By adding iodine to salt, a simple and inexpensive method was created to reduce the incidence of iodine deficiency globally.

What is radioactive iodine, and how is it used in thyroid treatment?

Radioactive iodine is used in thyroid ablation therapy to treat thyroid cancer. It is administered to destroy thyroid tissue, including cancerous cells, by emitting radiation. However, this treatment can lead to hypothyroidism as a side effect.

Why is potassium iodide given in the event of a nuclear disaster?

Potassium iodide is given during nuclear exposure to block radioactive iodine from binding to the thyroid gland. By saturating the thyroid's iodine receptors, it prevents the uptake of harmful radioactive iodine, thereby protecting the gland from radiation damage.