A number of additional tests are used to help make a diagnosis of thyroid cancer, and these may be done at different times by different medical specialists.
Palpation (manually inspecting the neck)
Palpation involves the doctor touching your neck to feel whether the thyroid is enlarged and whether they can feel any thyroid nodes.
Blood levels are analysed in the laboratory in order to determine whether the thyroid is working properly and whether hormone levels in the body are normal, raised or lower than usual.
A neck ultrasound uses soundwaves to build up a picture of your thyroid tissue and it can detect abnormal changes and nodules if they are present. Sometimes the blood flow to the thyroid is looked at, at the same time.
The only way to be sure about a diagnosis of thyroid cancer is to take a tissue sample (called a biopsy) and analyse it under a microscope.
Fine needle aspiration
This procedure is usually performed in a doctor’s office or clinic. A local anaesthetic may be injected into the skin to numb the area and your doctor will then insert a thin needle into the nodule to extract cells and some fluid. This might be repeated two or three times to obtain samples from different areas of the nodule. Test results can be positive (meaning there are cancerous cells), negative (meaning there are no cancerous cells), or undetermined (meaning it is not clear whether cancer is there). Although thyroid nodules are very common, less than 1 in 10 harbours a thyroid cancer.
Molecular diagnostics for unclear results
While not yet widely available, new tests that examine genes in the DNA of thyroid nodules are being developed. These tests can provide helpful information about whether cancer may be present or absent. These tests are particularly helpful when the specimen evaluated by the pathologist is undetermined (unclear). These specialized tests are done on samples obtained during the normal biopsy process. There are also specialized blood tests that can assist in the evaluation of thyroid nodules. These are currently available only at highly specialized medical centres, however the availability is increasing rapidly. Ask your doctor if these tests are available and might be helpful for evaluating your thyroid nodule.
If the needle aspiration biopsy is not clear, your doctor might suggest a biopsy in which the nodule and some of the surrounding thyroid tissue is removed. This procedure is usually done under general anaesthetic and you may need to stay in the hospital overnight.
Whole body scan – occasionally performed
If thyroid nodules are detected, a whole body scan (scintigraphy) can be performed as this provides a more detailed picture of the thyroid tissue. This imaging procedure involves being given a radioactive substance by injection or capsule which is taken up by the thyroid. Your thyroid tissue then emits gamma rays which are detected by a gamma camera and converted into an image.
This procedure was commonly performed in the past but the use of modern neck ultrasound and biopsy have proven so accurate and sensitive that scintigraphy is rarely used as a first choice evaluation tool in most situations. However, nuclear scanning still plays an important role in the evaluation of rare nodules that cause hyperthyroidism.