Thyroid Function Test

What is the Thyroid Function test?

This tests the active unbound or ‘free’ form of two main hormones that are produced by the thyroid gland, FT3 (Free Triiodothyronine) and FT4 (Free Thyroxine), as well as TSH (Thyroid Stimulating Hormone) which is produced by the pituitary gland. The role of TSH is to control the release of the thyroid hormones (T3 and T4). So if TSH is raised, it is trying to stimulate the thyroid gland to secrete higher levels of T3 and T4. If TSH is low, it is trying to reduce the levels of T3 and T4 in the body. The main conditions that these tests can identify are hyperthyroidism (where the thyroid is producing too many hormones) or hypothyroidism (where the thyroid gland is not producing enough thyroid hormones).

 
 

What biomarkers are measured in this test?

  • Free Thyroxine (Free T4)
  • Free Triiodothyronine (Free T3)
  • Thyroid Stimulating Hormone (TSH)
 
 

Who should take this test?

This test is useful for people who have concerns about changes in weight, who have a family history of thyroid problems, or who are taking medication for their thyroid and would like to monitor their thyroid status. If you have unexpected weight loss, please tell your doctor immediately.

 
 

Is there anything I need to know before taking this test?

If you have symptoms of unexpected weight loss, you should discuss this with your doctor immediately; don’t wait for the results of these tests. Any results should be discussed with your doctor. Discuss with your doctor the need to stop Biotin (Vitamin B9) medication prior to taking this test. Continue to take your normal thyroid medication, do not stop it for this test. It is recommended to delay this test by one month if you have had a recent illness or infection.

You must be at least 18 years old to use our testing services.

 
 

How often should I take this test?

Those people with a family history or concerns about possible thyroid disease may wish to take this test annually. If you have a thyroid condition you should discuss the frequency of testing with your doctor; they may suggest testing every 6 months.

 
 

What could results out of range (abnormal) mean?

Low T3 and T4 results may suggest that your thyroid gland isn’t as active as it should be (hypothyroidism). Where the TSH levels are high, it suggests that it is trying to simulate the thyroid gland to produce more hormones because the levels of T3 and T4 are too low. 

The opposite is where T3 and T4 levels are high (hyperthyroidism), which most commonly leads to TSH levels declining to try to bring the thyroid under control. Discuss these results with a doctor as soon as possible.

 
 

What could results in range (normal) mean?

Normal T3, T4 and TSH are suggestive of a healthy thyroid gland. But if you have symptoms you must discuss these with your doctor as soon as possible, to help investigate the cause of your symptoms.

 
 

How can I improve my results?

While medication may be necessary for managing thyroid conditions, there are several lifestyle changes and practices that can optimise thyroid hormone levels and support overall thyroid health. These include:

Eating a balanced and nutrient-rich diet: Consuming a variety of fruits, vegetables, lean proteins, and healthy fats can provide essential nutrients and support thyroid function.

Managing stress: Chronic stress can disrupt thyroid hormones, so practising stress-reducing techniques such as meditation, deep breathing, or yoga can be helpful.

Getting adequate sleep: Sleep plays a crucial role in hormone regulation, including thyroid hormones, so getting enough quality sleep is important for maintaining healthy levels.

Exercising regularly: Regular physical activity can boost metabolism and support healthy thyroid function.

Monitoring thyroid function regularly: Regular monitoring of thyroid hormone levels and thyroid-stimulating hormone (TSH) levels can help detect any changes or abnormalities early on, allowing for prompt intervention and management.

By incorporating these practices into your daily routine and working closely with your healthcare provider, you can optimise your thyroid hormone levels and support overall thyroid health.

 
 

What other tests could I consider? 

Patients who check their thyroid gland may also wish to check their Cholesterol, HbA1c and Vitamin D levels.

 
 

To purchase this test, please click here.