Thyroid conditions are common and can affect people of all ages from babies to the elderly. They can be caused by a range of underlying conditions. Your doctor will usually start by requesting a TSH test. This measures the amount of Thyroid Stimulating Hormone (TSH) in your blood. TSH is the hormone that stimulates your thyroid gland to make thyroid hormone. This is the only thyroid test covered by Medicare if you do not have a history of thyroid problems. Depending on your symptoms and your TSH result, you may need further testing of your thyroid hormones with measurement of FreeT4 and Free T3. If your doctor thinks you could have an autoimmune condition that is affecting your thyroid gland you may go on to have thyroid antibody tests. There are also tests that are used to monitor thyroid cancer following treatment. They include thyroglobulin and calcitonin tests which are used to detect and monitor some rare forms of thyroid cancer.
Why get tested?
Your thyroid is a small gland at the base of your throat. It uses iodine from your diet to make hormones that regulate many of your body’s metabolic processes – your body’s processes for breaking down food and converting it into energy. How your thyroid is working affects how fast you burn calories, your heart rate, blood pressure and body temperature.There are two main hormones produced by the thyroid. These are T4 and T3. They circulate in your blood, and it is important that levels stay constant to keep your metabolism running and in balance.
There is a feedback mechanism to make sure they don’t get too high or too low.
Having the test
Reading your test report
No single pathology test can accurately diagnose all types of thyroid conditions. A combination of tests is usually needed to detect disorders of thyroid function and to differentiate between thyroid and pituitary gland problems. It is usually followed by a free T4 and/or free T3 tests) to investigate the cause. A ‘free’ T4 or T3 test refers to the fact that these hormones are circulating freely and available to be absorbed by body tissues.
Your results will be presented along with those of your other tests on the same form. You will see separate columns or lines for each of these tests.
High TSH result
Low TSH result
Patterns of thyroid function tests results and their most common causes.
Your results will be compared to a reference interval (sometimes called a normal range or reference range).
If your results are flagged as high or low this does not necessarily mean that anything is wrong. It depends on your personal situation. Your results need to be interpreted by your doctor.
Questions to ask your doctor
The choice of tests your doctor makes will be based on your medical history and symptoms. It is important that you tell them everything you think might help.
You play a central role in making sure your test results are accurate. Do everything you can to make sure the information you provide is correct and follow instructions closely.
Talk to your doctor about any medications you are taking. Find out if you need to fast or stop any particular foods or supplements. These may affect your results. Ask:
Any more to know?
Results for TSH may be low during the first trimester of pregnancy. This is because one of the hormones of pregnancy (HCG) has a TSH-like affect so the pituitary is not required to produce as much TSH.
Pathology Tests Explained (PTEx) is a not-for profit group managed by a consortium of Australasian medical and scientific organisations.
With up-to-date, evidence-based information about pathology tests it is a leading trusted sources for consumers.
Information is prepared and reviewed by practising pathologists and scientists and is entirely free of any commercial influence.