Which isotope is commonly used in studies of the thyroid gland?

The isotope commonly used in studies of the thyroid gland is Iodine-131. This isotope is particularly useful because the thyroid gland naturally absorbs iodine from the bloodstream to synthesize thyroid hormones. Iodine-131 is a radioactive form of iodine that emits both beta and gamma radiation, which allows it to be used both diagnostically and therapeutically.

In diagnostic applications, Iodine-131 can help visualize the functioning of the thyroid gland through imaging techniques, allowing healthcare providers to assess conditions such as hyperthyroidism or the presence of thyroid nodules. Additionally, because of its radioactivity, Iodine-131 is also employed in the treatment of thyroid cancer and hyperthyroid conditions by selectively destroying overactive or malignant thyroid tissue.

The other isotopes listed do not have the same biological significance or practical application in thyroid studies. For example, Carbon-14 is more commonly used in radiocarbon dating and tracking biological processes involving carbon. Iodine-141 is less commonly used than Iodine-131 in medical settings, and Uranium-235 is primarily associated with nuclear energy, rather than medical applications. This specificity makes Iodine-131 the preferred choice for thyroid gland studies.