Blood tests are not used to screen for thyroid cancer, but they can help show if the thyroid is working normally and can help the doctor decide what other tests may be needed. They can also be used to control certain types of cancer. There is no blood test that can detect thyroid cancer, but your doctor may want you to do one to help determine if the thyroid gland is working properly. A blood test cannot diagnose thyroid cancer, but it will measure the level of TSH, a hormone produced by the pituitary gland near the brain.
Thyroid nodules are very common and occur in up to 50% of people, with only 5 to 10% of them being cancerous. Thyroid biopsy is the procedure of choice to identify patients who require surgery for possible cancer, but it is not a perfect test. When the diagnosis of biopsy is questioned, some patients undergo what is ultimately discovered to be a benign disease. The search for alternative methods of confirmation before surgery remains a goal for the diagnosis of thyroid nodules and thyroid cancers.
MicroRNAs (miRNAs) are small fragments of genetic material that leak out of cells and are found in the bloodstream. Thyroid cancer cells can release miRNAs, and these miRNAs have been a focus of research to find a marker of thyroid cancer in the bloodstream. In this study, serum miRNA tests were performed to determine if a diagnosis of thyroid cancer can be made or confirmed simply by drawing blood from a patient. A blood test called a thyroid function test is used to check the levels of thyroid hormones in the blood.
Tumor markers are substances found at higher than normal levels in the blood, urine, or body tissues of some people with cancer. This test for thyroid cancer is usually used to see if the disease has spread to other areas of the body, but sometimes it can also be used to guide the biopsy needle. During a thyroid scan, your doctor gives you a small amount of radioactive iodine, either by mouth or by injection. Two of the miRNA markers (miRNA-95 and miRNA-190) were found to be highly correlated with thyroid cancer and were 95% accurate in making a cancer diagnosis.
The test can be positive, which means there are cancer cells, or negative, which means there are no cancer cells. Thyroglobulin (Tg) is a protein naturally produced by the thyroid, as well as differentiated thyroid cancer. If your doctor is concerned about TCM, you may need to undergo advanced genetic testing and a blood test for tumor markers, such as carcinoembryonic antigen (ACE) protein and the hormone calcitonin. In general, even if there is thyroid cancer present, the thyroid works normally and hormone production will not be affected. However, this blood test can rule out benign thyroid conditions such as hypothyroidism or hyperthyroidism. Remember that the lump in your neck is most likely not thyroid cancer, but you're doing the right thing to get it checked.
This cannot be emphasized enough, but an ultrasound tells the doctor if there is anything abnormal in the thyroid (diagnosing thyroid cancer). Questions may relate to whether you have been exposed to too much radiation or if you have a family history of thyroid cancer or thyroid disease.