VISIT YOUR GP

Statistics show that well over 1 million Australians are living with an undiagnosed thyroid disorder. 

If you have either hypothyroid or hyperthyroid thyroid symptoms, or physical changes to your thyroid gland, please visit your GP to discuss and ask to have specific thyroid pathology tests and/or a thyroid ultrasound to either determine or eliminate a thyroid disorder.

Thyroid Disorders can be difficult to diagnose, due to many symptoms being similar to those of other medical conditions.

The Australian Thyroid Foundation recommend diagnosis using biochemical pathology testing (serum TSH, T4, T3 and Thyroid Antibodies). A thyroid ultrasound is essential to determine the structure of the gland and define any physical abnormalities within the gland. If further testing is required your treating doctor may order additional screening with radionuclide scans or CT to determine an accurate diagnosis.

Speak to your GP about your symptoms, your family history, if any member of your family has an Autoimmune Disease, a Thyroid Disease or Thyroid Cancer.

Clinical Diagnosis

• Palpate or feel your neck for any sign of swelling or lumps

PATHOLOGY

Blood Tests

• Thyroid stimulating hormone (TSH): This test is the initial indicator or thyroid disorders. TSH is produced by the anterior pituitary gland after stimulation from thyrotropin releasing hormone (TRH) secreted by the hypothalamus. TRH then triggers the pituitary gland to release TSH. The level of TSH rises when thyroid hormone levels (T4) in the blood decline. Conversely, the level of TSH declines as the thyroid hormone (T4) level in the blood rises.
  
• Thyroxine (T4): This test is used for a patient’s initial diagnosis and for monitoring thyroid replacement hormone levels (Levothyroxine) in the blood.
• Total T4 - Measures the total amount of thyroxine in the blood. This includes the amount attached to blood proteins that help transport the hormone through the bloodstream.
  
• Free T4 - Measures thyroxine that is not attached to proteins. This level of free hormone is what exerts the biological effect. This test shows how the hormone affects the functioning of many types of body cells.
  
• Triiodothyronine (Free T3): Measures the level of T3 in the blood. This test is useful for confirming an overactive thyroid (hyperthyroidism/Graves’ Disease). It also shows Levothyroxine absorption.
  

• Antithyroglobulin (anti-Tg) antibodies: This test is used to diagnose autoimmune thyroid disease. (Graves’/Hashimoto’s Diseases). 

• Antithyroid peroxidise (anti-TPO) antibodies: This test is used to diagnose autoimmune thyroid disease, in particular Hashimoto’s Disease.

The Thyroid Jigsaw

Time to Have Pathology Tests?

Thyroxine Replacement Hormone, Oroxine, Eutroxsig, Eltroxin & Levoxine SHOULD NOT BE TAKEN BEFORE A THYROID FUNCTION PATHOLOGY TEST.

It is recommended to fast after your evening meal the night before the test.  You can drink water throughout the night, up until the time of the test.

Have your test as early as possible in the morning, ideally 7.30-8.00 am. Take your daily dose after the test is complete and wait at least 30 – 60 minutes before you have breakfast.  

If you take your daily dose before the test, you may receive an incorrect result, which could indicate a change in dose, which may not be necessary.

Ultrasound & Scanning

Ultrasound - A thyroid ultrasound is performed by a specialist ultrasonographer or qualified Endocrinologist. An ultrasound is used to measure the size, shape and texture of the thyroid gland, as well as detecting any nodules and cysts within the gland. Soundwaves are used to build a picture of the thyroid gland. This procedure is non-invasive and painless. A gel is wiped over the neck area and a hand held probe is used to scan the thyroid area to determine diagnosis.

Nodules need to be monitored regularly or treated. A Thyroid Pathology Test cannot show any physical change to the thyroid gland and therefore a thyroid ultrasound is an important diagnostic test.

If you have an enlarged thyroid gland, discomfort or pain in your neck, a stubborn cough, trouble speaking or breathing, please ensure your doctor orders a Thyroid Ultrasound. Results may indicate treatment is necessary or regular monitoring is needed, which should not be overlooked.

Imaging of the thyroid gland and adjacent structures in the neck by nuclear medicine radioisotope scans, computerised tomography (CT) and Magnetic Resonance Imaging (MRI) scans

Your treating Doctor may request some form of imaging investigation to confirm or exclude abnormal function or structure of your thyroid gland. By far the commonest and most helpful form of imaging the thyroid and other soft tissues in the neck is by an Ultrasound examination.

Radioisotope scans of the thyroid are Nuclear Medicine investigations used to investigate the functional ability of the thyroid to take up the radioisotope of iodine and also to outline increased or decreased activity of the whole thyroid gland or of individual and multiple thyroid nodules. These scans are frequently performed as a follow-up looking for any residual thyroid tissue after surgical removal of the thyroid for cancer and subsequent radiation treatment. A low dose of radioactive iodine – usually 131I in Australia-  or Technetium Tc99m is administered orally so that the isotope uptake into the thyroid can be measured, and images of the thyroid gland can be obtained by special Nuclear Medicine instruments.

A Nuclear Medicine Sestamibi Parathyroid scan is used to localise parathyroid tumours in the neck usually behind or adjacent to the thyroid gland. This is called a Sestamibi scan because the radioactive material Tc99m-sestamibi is used for imaging. Identification and localisation of the parathyroid tumour enables the surgeon to undertake minimal-access surgical removal of the parathyroid tumour. 

Computerized Tomography (CT) scans of the thyroid and adjacent structures in the neck may be required to determine the structure and position of an enlarged thyroid gland (goitre) and to determine if a goitre is pressing on and obstructing the windpipe (trachea) or extending retrosternally into the chest cavity. For these CT scans, and generally most diagnostic CT scans for other purposes, a radiocontrast agent is usually administered intravenously prior to the CT scan. These radiocontrast agents enhance the quality of the CT images, but they contain large concentrations of iodine and can precipitate hyperthyroidism (overactivity of the thyroid gland) in patients with Graves’ disease or autonomously functioning nodular goitres. The need for administration of radiocontrast agents should be discussed with the Doctor when the CT scan is ordered in patients who may be at risk of developing hyperthyroidism from the iodine in the contrast solution.

Magnetic Resonance Imaging (MRI) scans use strong magnetic fields and radio waves to produce images of internal organs, as well as blood vessels, muscles, tendons, and other soft tissues in the body. There is no radiation or Xrays involved and contrast agents if used do not contain iodine. MRI scans cannot be used in patients with metallic implants such as pacemakers. They are rarely used for imaging in patients with thyroid disorders except for patients with thyroid cancer which may have recurred or spread to other organs.

Please Note: If you have been diagnosed with Graves’ Disease, Hyperthyroidism, a Nodular Goitre or Heart Disorder, please speak to your doctor about performing the CT Scan or MRI Scan without Iodine Contrast Solution. The Iodine Contrast Solution can cause hyperthyroid symptoms which can be harmful. The CT Scan or MRI Scan can be performed without the iodine contrast solution.

Read Q&A about Iodine Contrast Solutions – Used in CT Scans & Other X-Rays by Professor Jim Stockigt.

All patients with hyperthyroidism and heart conditions need to be aware of issues relating to these solutions.

Fine Needle Biopsy - Fine needle biopsy, also known as fine-needle aspiration cytology (FNAC), is usually done with the aid of ultrasound by a specialist doctor. A very fine needle is inserted into the thyroid gland to extract tissue from a nodule/s. This tissue is sent to a pathologist for testing. A FNB is used in the diagnosis of nodules and in particular identifying cells that may be cancerous.

REMEMBER

It is not the fact that your Thyroid Pathology results sit in the normal reference range, but where in the normal range your results sits! Please refer to the Thyroid Jigsaw, above.

Please Note:  Reference ranges for children and pregnant women may vary from the normal adult reference range.  Laboratory reference ranges can also vary.  Always use the reference range as your guide in regard to the ATF recommendations for your best result and consult your thyroid treating doctor.

Thyroid Antibodies TPO & TGO - A positive result indicates Autoimmune Thyroid Disease, either Hashimoto's or Graves' Diseases.

Thyroid Ultrasound  -  A Thyroid Ultrasound shows the size, shape and texture of the thyroid gland and if nodules or cysts are detected in your thyroid gland.  This test is an important as all the pathology tests. So if you have an enlargement of your thyroid gland or discomfort in your neck, a cough, or have trouble speaking or breathing, please speak to your doctor about ordering a Thyroid Ultrasound.