Symptoms and signs such as fatigue, anxiety or depression, unexplained weight gain or loss, change in bowel movements, difficulty sleeping, muscle aches, and joint stiffness may signify that you have a thyroid disorder. Once you suspect that your thyroid gland is not functioning properly, it is important to get a professional diagnosis and thyroid investigations so that you can work towards alleviating your symptoms.
Thyroid function tests
Doctors will be able to ensure a proper diagnosis through a series of tests. Blood tests are common when it comes to diagnosing thyroid problems. When the thyroid gland is not functioning properly, either too little or too much thyroid hormone is produced.
In addition, TSH (thyroid-stimulating hormone) levels are also thrown out of balance when a thyroid problem exists. Blood tests can measure both thyroid hormone and TSH levels to determine how the thyroid gland is functioning. For instance, if you have hyperthyroidism, then your thyroid hormone levels will be abnormally high and your TSH levels will be abnormally low.
If the blood test shows that you have hyperthyroidism, then a radioactive iodide uptake test is typically performed in order to determine the underlying cause of the condition. For this test, you will need to swallow the iodide pill. Then, the doctor will measure your thyroid gland activity using an instrument that is placed over your neck. This test will determine how much of the iodide is absorbed by your thyroid.
If the test shows that you thyroid gland is absorbing excessive quantities of the iodide, then the iodide uptake test will indicate where most of the iodide is collecting in your thyroid gland. This will show what part of your gland is producing the excess amounts of thyroid hormone. Determining the precise cause of your symptoms and the exact location of the thyroid problem will allow your doctor to design the most effective treatment plan. With time and by following the treatment plan, you will be able to find relief from your symptoms.
Thyroid blood tests
- Thyroid function tests are measured by a blood test
- The standard Thyroid Function Tests which are performed in Australia are:
- Thyroid Stimulating Hormone (TSH)
- Free Thyroxine (Free T4 or FT4)
- Free Triiodothyronine (Free T3 or FT3)
- The Medicare protocol for screening patients who have not yet been diagnosed with a thyroid function problem is to test TSH first and only if the result of this test is outside the reference range then to test Free T4
- Thyroglobulin antibodies are the antibodies to the major component of thyroid colloid and precursor of thyroid hormones
- These are found in most people with Grave’s disease and nearly all with Hashimoto’s thyroiditis
- Thyroglobulin antibodies are also used as a marker to detect residual or recurrent tumour in patients who have undergone treatment for differentiated thyroid cancer
Thyroid peroxidise (TPO)
- Antibodies to thyroid peroxidise are found in most patients with Grave’s disease or Hashimoto’s thyroiditis
- Raised titres of thyroid peroxidise are also found after childbirth and in autoimmune diseases such as rheumatoid arthritis
Thyroid stimulating hormone receptor antibodies (TRAbs)
- Most TSH receptor antibodies have a thyroid stimulatory action
- In some instances TRAbs bind to the receptor and block activity
- Measurement of TRAbs is helpful in the diagnosis of Grave’s disease, being detected in 90% of patients
If you have any questions about thyroid investigations or thyroid or parathyroid surgery, you should speak to your local doctor, who will arrange to contact your thyroid surgeon.