In case of thyroid scan, the person will either swallow or injected a small amount of radioactive iodine. There is a special camera which will measure the amount of iodine taken up by the thyroid. The scan may show the areas within the thyroid without iodine uptake. It called cold spots and can represent cancer. But all cold areas are not cancerous, so a biopsy of these is needed. A whole body scan or check up are very helpful after a diagnosis of cancer is made, I will help to find if the cancer has spread to places the thyroid gland. Blood test, thyroglobulin test are also usually done.
Most of the thyroid nodules or lumps are benign but the risk increases if they occur in people below 30 or above 60. Women have more chance to develop thyroid cancer than men at younger age ( ie 40-50 years old women versus 60-70 men)