Thyroid nodules are common outgrowths that develop on your thyroid gland. These lumps occur in approximately half of the planet's population. The precise cause of thyroid nodules is unknown. They are frequently associated with an iodine deficiency and in people with a family history of thyroid nodules. These outgrowths also occur in people with an existing thyroid disease. Your risk for developing this common nodule increases with age. Approximately 95% of these nodules are noncancerous. There are several indicators that a thyroid nodule is malignant. A nodule that is hard, fixed or fails to shrink after you receive thyroid hormone medication is suspicious and warrants further investigation. Blood tests, biopsies and ultrasounds can further clarify the status of your thyroid nodule. Your doctor will check your thyroid hormone to determine whether it is functioning as it should. Normal thyroid function does not rule out the possibility of cancer. During the biopsy, your physician will remove a minute portion of your thyroid gland for testing. An ultrasound is used to capture an image of your thyroid gland. The image allows physicians to determine the vascularity, shape, size and other characteristics of your thyroid. It can not definitively determine whether a thyroid gland is cancerous. A radioactive iodine scan also provides information on thyroid function. Your physician will instruct you to drink radioiodine. The level of iodine that your thyroid absorbs is a good indicator of its health. A nodule that doesn't absorb the iodine is classified as "cold". Approximately 10% of these nodules are cancerous. Benign nodules are usually asymptomatic, but some people report anxiety, shortness of breath and weight loss. Most nodules are discovered during regular neck exams or during diagnostic testing for other medical conditions. This indicates that the majority of people with thyroid nodules aren't aware that they have them. Most nodules escape detection because they are quite small. Others are readily apparent. You can see the nodule when you look at your throat in the mirror. These nodules can press against your windpipe and make it difficult for you to swallow, speak or breathe.