Have you used a home testing kit for a medical diagnosis?

COVID-19 RATs are an example of these types of tests but we are interested in the many others on the market.

The University of Wollongong is conducting a small study about them and we'd like to hear from you if you have used one or considered using one.

Simply complete a short survey at:

From here, we may invite you to take part in a paid interview.

For more information, contact Dr Patti Shih: pshih@uow.edu.au

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At a glance

Why get tested?

To screen for and diagnose thyroid disorders; to monitor treatment of hypothyroidism and hyperthyroidism

When to get tested?

For screening: newborns; there is currently no recommendation in Australia for routine screening of adults. For monitoring treatment: as directed by your doctor; otherwise, as symptoms present.

Sample required?

A blood sample drawn from a vein in the arm or from pricking the heel of an infant

Test preparation needed?


Quick Read patient information sheet

What is being tested?

The test measures the amount of thyroid-stimulating hormone (TSH) in your blood. TSH is made by the pituitary gland, a small organ located just below the brain. TSH is one of the pituitary gland’s messengers — it tells the thyroid gland to start making thyroid hormone. There is a feedback system between the pituitary gland and the thyroid gland. If too much thyroid hormone (tri-iodothyronine or T3 and thyroxine or T4) is being produced by the thyroid this sends a signal to the pituitary gland which turns down the production of TSH. Conversely, if too little T3 and T4 are being produced the pituitary gland steps up production of TSH. In healthy people this system regulates itself perfectly. However, in thyroid or pituitary diseases the system becomes unbalanced. The pattern of changes can help diagnose the underlying problem. See the table in the next tab "The test/What does the test result mean?"

Talking Results: what your Thyroid Function Test results can show

How is the sample collected for testing?

A blood sample is obtained from a needle placed in a vein in your arm or from pricking the heel of an infant.

Is any test preparation needed to ensure the quality of the sample?

No test preparation is needed.

The Test

How is it used?

Thyroid stimualting hormone (TSH) testing is used to:

  • screen newborns for an underactive thyroid gland
  • diagnose a thyroid disorder in a person with symptoms
  • monitor thyroid replacement therapy in people with hypothyroidism
  • as part of the investigation of female infertility problems
  • help to evaluate pituitary function (occasionally)

When is it requested?

Your doctor requests this test if you show symptoms of a thyroid disorder. For example, symptoms of hyperthyroidism include heat intolerance, weight loss, rapid heartbeat, nervousness, sweating and increased frequency of stools.

Common symptoms of hypothyroidism include fatigue, weakness, weight gain, muscle aches, constipation, slow heart rate and cold intolerance.

The blood test is often requested with other thyroid hormone tests and after a physical examination of your thyroid. TSH screening is routinely performed in newborns. There are currently no recommendations for routine screening of adults in Australia.

What does the test result mean?

A high TSH result often means an underactive thyroid gland caused by failure of the gland (hypothyroidism). Very rarely, a high TSH result can indicate a problem with the pituitary gland, such as a tumour, in what is known as secondary hyperthyroidism. A high TSH value can also occur in people with underactive thyroid glands who have been receiving too little thyroid hormone medication.

A low TSH result can indicate an overactive thyroid gland (hyperthyroidism) or damage to the pituitary gland that prevents it from producing TSH. A low TSH result can also occur in people with an underactive thyroid gland who are receiving too much thyroid hormone medication.

An abnormal TSH usually indicates a deficiency or an excess of thyroid hormones available to the body but it does not indicate the reason why. An abnormal TSH result is usually followed by additional testing of free thyroxine (FT4) and/or free tri-iodothyronine (FT3) to investigate the cause. The combination of a TSH test and tests for the thyroid hormones T3 and T4 is known as a thyroid function test (TFT).

The following table summarises patterns of thyroid function test results and their most common causes.

TSH FT4 FT3 Interpretation
High Normal Normal Mild (subclinical) hypothyroidism
High Low Low or normal Hypothyroidism
Low Normal Normal Mild (subclinical) hyperthyroidism
Low High or normal High or normal Hyperthyroidism
Low Low or normal Low or normal Nonthyroidal illness; rare pituitary (secondary) hypothyroidism
About Reference Intervals

Is there anything else I should know?

Thyroid-hormone replacement therapy and some drugs may interfere with thyroid function test results, so tell your doctor about any drugs you are taking.

When your doctor adjusts your dose of thyroid hormone, it is important that you wait at least one to two months before checking your TSH again, so that your new dose can have its full effect.

Extreme stress and acute illness may also affect TSH test results. In this event, TSH should be rechecked a few weeks after the illness has resolved. 

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 effect so the pituitary is not required to produce as much TSH. TSH results in pregnancy should be interpreted in relation to reference intervals specific for pregnancy.

Common Questions

How is hyperthyroidism treated?

Hyperthyroidism can be controlled through treatment. This will normally involve tablets to stop the thyroid gland producing thyroid hormones, radioactive iodine treatment to destroy thyroid tissue, or surgery to remove part or all of the thyroid gland.

How is hypothyroidism treated?

Hypothyroidism is easily treated and controlled for most people with thyroxine (T4) replacement in the form of a tablet.

Do doctors test for TSH levels during pregnancy?

Yes, that is a good way to test for hypothyroidism during pregnancy, which is often overlooked.

For more information, see British Thyroid Foundation: Thyroid in Pregnancy

Last Review Date: January 11, 2023

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