Final answer:
The first step in evaluating most thyroid nodules is to use nuclear diagnostic imaging with radioactive iodine to assess the gland's activity and structure.
Step-by-step explanation:
The first step for most thyroid nodules is to perform diagnostic imaging using radioactive isotopes, like radioactive iodine. The thyroid gland has a high affinity for iodine, making it ideal for imaging with isotopes such as Na¹¹³I or Na¹²³I. Through a process called nuclear diagnostic imaging, the iodine is absorbed by the thyroid gland, allowing for the detection of abnormal growths or activity within the gland itself.
This process is significant as it helps in diagnosing conditions such as hyperthyroidism, characterized by excessive uptake of iodine, or hypothyroidism, indicated by lack of iodine uptake. Blood tests are also necessary to confirm the diagnosis and to monitor the levels of thyroid hormones. Sometimes, radioactive iodine is also used in the treatment of certain thyroid conditions.