All main services are operating. Click here for more information.
your discount will be applied at checkout
your 10% discount will be applied at checkout

How Often Should a Thyroid Test Be Carried Out?

The thyroid gland has many important functions within the human body. Most importantly, it produces and secretes hormones into the blood which influence the metabolism of cells.

Head and shoulder shot of a woman standing with her eyes closed

In this article we look at how often you should get a thyroid test and the symptoms of an overactive or underactive thyroid. We also explain what the thyroid gland is and the role it plays within the body along with the three hormones produced by the thyroid gland.

How Often Should A Thyroid Test Be Carried Out?

How often you will need to have a thyroid test following diagnosis of either an overactive or underactive thyroid will depend on your condition and treatment.

If you are diagnosed with a thyroid condition you will be prescribed treatment with the aim of making you feel better and preventing any long-term damage.

TSH is the most sensitive biomarker for thyroid function and is often used to ensure the hormone replacement therapy you are prescribed is working as effectively as it should.

If you have an underactive thyroid you will need to have your TSH levels tested once a year to make sure they are within the normal parameters.

How Often Should T3 Levels Be Checked?

Thyroid problems can be identified by measuring the level of free T3 (FT3) in the blood. High levels indicate an overactive thyroid whereas low levels indicate an underactive thyroid.

T3 can be used to:

  • test to see if your thyroid is performing properly
  • diagnose an overactive thyroid (hyperthyroidism)

T3 is only really requested when diagnosing or testing the severity of hyperthyroidism.

How Often Should T4 Levels Be Checked?

Equally, T4 is also used to identify thyroid issues and can be used to detect both an underactive thyroid (hypothyroidism) and overactive thyroid (hyperthyroidism).  Again, it’s the free T4 (FT4) which affects the functions in the body.

High levels of T4 indicate an overactive thyroid and low levels of T4 indicate an underactive thyroid. However, the levels of T4 are often used in conjunction with presenting symptoms to identify a thyroid problem, rather than alone.

If you are diagnosed with hyperthyroidism, you will usually be offered TSH and T4 tests, but how often they are performed will depend on the treatment you are receiving.

If hypothyroidism is diagnosed, you will usually begin taking levothyroxine a synthetic, man-made version of the thyroid hormone thyroxine.

If hyperthyroidism is diagnosed, however, treatment options include:

  • Antithyroid Drugs
  • Surgery to remove some of or all the thyroid gland
  • Radioactive iodine to reduce the thyroid’s activity

When treatment commences, it is likely you will have blood tests on a regular basis, possibly every few weeks to assess your body’s response to treatment.

Once the treatment has made your condition stable, the frequency of the blood tests should reduce.

What Are They Symptoms Of An Overactive Thyroid?

Overactive Thyroid or Hyperthyroidism

An overactive thyroid is a condition called Hyperthyroidism and is where the thyroid is overactive and produces too much of the thyroid hormones.

When too much of the T3 and T4 hormones are produced, the following symptoms can occur:

  • Feeling nervous, anxious or irritable
  • Weight loss
  • Hyperactive
  • Mood swings
  • Diarrhoea
  • Fatigue
  • Weak muscles
  • Itchiness
  • Low sex drive
  • Need to pee more often
  • Increased thirst

What Are They Symptoms Of An Underactive Thyroid?

Underactive Thyroid or Hypothyroidism

Hypothyroidism or an underactive thyroid, on the other hand, is characterised by the failure of the thyroid to produce enough T3 or T4 hormones. As a result, symptoms can include:

  • Fatigue
  • Feeling cold
  • Depression
  • Weight gain
  • Muscle cramps and aches
  • Low sex drive
  • Brittle hair and nails
  • Dry skin
  • Irregular or heavy periods

What Is A Thyroid Test?

A thyroid blood test can determine the function of the thyroid. The test measures the levels of TSH, T4 and T3 in the blood. The free portions of T3 (FT3) and T4 (FT4) are usually measured as this is the active part of each hormone.

Laboratories use reference ranges when analysing the function of the thyroid. Typical reference ranges for a healthy individual may look like this:

  • TSH 0.27– 4.2 mIU/L
  • FT4 12.0 – 22.0 pmol/L
  • FT3 3.1 – 6.8 pmol/L

Different laboratories use different reference ranges, but if your results fall outside of these parameters you could be diagnosed with hypothyroidism or hyperthyroidism. Subclinical hypothyroidism, on the other hand, occurs when your blood TSH level is slightly raised but your FT4 is within the normal range.

How Much Does Private Thyroid Testing Cost?

Private thyroid testing might not cost as much as you expect. And you may also be surprised to hear you can carry out the test itself using a finger prick kit at home, saving the cost and inconvenience of visiting a clinic.

Thyroid Blood Test - £49

Our private thyroid test is just £49 and tests for Triiodothyronine (T3), Thyroxine (T4) and Thyroid stimulating hormone (TSH).

Advanced Thyroid Blood Test - £65

Our advance thyroid test is £65 and as well as testing for FT3, FT4 and TSH it also tests for Thyroglobulin Antibodies and Thyroid Peroxidase Antibodies.

What Is The Role Of The Thyroid Gland?

The thyroid is located at the front of the neck and consists of two lobes, one on each side of the windpipe and adjoined by a small strip of thyroid tissue known as the isthmus.  The three hormones produced by the thyroid are:

  • T3 (triiodothyronine)
  • T4 (tetraiodothyronine)
  • Calcitonin

T3 and T4 are the active forms of the thyroid hormone, thyroxine, and are involved in the regulation of:

  • The body’s metabolic rate
  • Heart function
  • Digestive function
  • Muscle control
  • Brain development
  • Bone maintenance


  • How often you check your thyroid is dependent on your condition; however
  • You should have a blood test at least once a year if you have already been diagnosed with a thyroid problem
  • You will need a TSH test once a year if you have an underactive thyroid
  • If you fall pregnant and have a thyroid disorder you should have a blood test during early pregnancy
  • Blood tests are the most accurate way to diagnose and manage thyroid disorders
  • Your symptoms and your general wellbeing are also key to your diagnosis
  • If you are taking medication and you’re still not feeling well, your doctor can change the dose to help manage the condition better
  • You shouldn’t alter your medication dose without consulting a doctor

Advanced Thyroid Check

This advanced thyroid blood test checks key thyroid hormones TSH, FT4 and FT3 together with thyroid antibodies to establish if your thyroid is functioning correctly.
Advanced Thyroid Check
5 Biomarkers Included
Test thyroid function together with thyroid antibodies.


  1. Informed Health Online [Internet]. Cologne, Germany: Institute for Quality and Efficiency in Health Care (IQWiG); 2006-. How does the thyroid gland work? 2010 Nov 17 [Updated 2018 Apr 19]. Available from:
  2. Lab Tests Online UK. (2019). Thyroid Function Tests. Available at:
  3. Society for Endocrinology. (2018). Triiodothyronine. Available at:
  4. Society for Endocrinology. (2018). Thyroxine. Available at:


Share on facebook
Share on twitter
Share on linkedin

Service Status

Kit Dispatch

Kits ordered before 2pm from Monday to Friday continue to be dispatched same day via First Class Royal Mail. After 2pm your kit will be dispatched the next working day. Orders placed on the weekend will be despatched Monday.

Postal Service

There may be some delays in parts of the UK while the Royal Mail catches up with their Christmas backlog. Click here for updates on the Royal Mail service.

Lab Analysis

Our labs are operating as normal.

Doctor/nurse reviews

Our doctors and nurses are currently working remotely and continue to review results.

Home phlebotomy appointments

Our home phlebotomy service is running but please be aware, if you or anyone in your household have experienced symptoms of COVID-19 within the last 14 days, due to the current government guidelines, we are unable to arrange an appointment at this time. Due to a high demand for nurses, along with current covid restrictions around the UK, there may be a delay in providing an appointment.

Customer service

Our customer service team are currently working from home, available to answer any questions via email.

Results dashboard

You can continue to access your results as normal either through your browser or via our iOS or Android app.


If you are an employer and would like to order multiple tests for your employees, please complete the form below.