Thyroid Blood Tests

Feeling tired, struggling with weight changes, or noticing shifts in your mood? A Medichecks thyroid test can check your hormones and antibodies, helping to identify signs of an underactive, overactive, or autoimmune thyroid condition.

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Take control of your thyroid
Advanced Thyroid Function Blood Test

Get detailed insights into your thyroid function, including antibodies and nutrients essential for optimal thyroid health

  • Results estimated in 2 working days
  • 10 biomarkers
£89.00
Check, monitor, treat
Thyroid Function Blood Test

Monitor your thyroid health and detect any imbalances with our Thyroid Function Blood Test

  • Results estimated in 2 working days
  • 3 biomarkers
£45.00
Thyroid Function with Antibodies Blood Test

Get a comprehensive view of your thyroid health with this advanced test with antibodies

  • Results estimated in 2 working days
  • 5 biomarkers
£65.00
Selenium Blood Test

Worried about low selenium levels? Selenium is an essential mineral that supports thyroid function, immune health, and antioxidant protection

  • Results estimated in 7 working days
  • 1 biomarkers
£101.00
“The thyroid plays a key role in regulating metabolism, energy levels, and hormonal balance. Blood testing can provide valuable insight into your thyroid function and support a better understanding of your overall health.”

Dr Natasha Fernando, Medical Director, Medichecks

Signs you might need a thyroid test

The thyroid gland helps regulate metabolism, energy levels, body temperature, and mood. When it's not working properly, symptoms can be subtle and easy to dismiss.

A thyroid test might be right for you if you've noticed:

  • Persistent fatigue or low energy
  • Unexplained weight gain or weight loss
  • Feeling unusually sensitive to cold or heat
  • Changes in mood, including low mood or anxiety
  • Brain fog or difficulty concentrating
  • Dry skin, hair thinning, or brittle nails
  • Changes in heart rate
  • Sleep disturbances

    A thyroid function test measures key markers such as TSH (thyroid stimulating hormone), Free T4, and Free T3. These markers help check whether thyroid levels are within normal range. We also offer advanced thyroid tests that check antibodies and thyroid-related nutrients.

Which thyroid test should you choose?
  • Thyroid Function Blood Test: A simple first step for an initial check if you have symptoms, or for monitoring an existing thyroid condition over time.
  • Thyroid Function with Antibodies: Includes thyroid hormones plus thyroid antibodies, which can help if you want to understand whether autoimmunity may be involved.
  • Advanced Thyroid Function: The most in-depth option, combining thyroid hormones and antibodies plus key nutrients linked to overall thyroid health for a more complete overview.

For more information on thyroid antibodies, this blog is a helpful read: All you need to know about thyroid antibodies.

FAQs

What does a thyroid blood test check for?

A thyroid blood test checks the hormones that help regulate your metabolism and energy, including TSH, Free T4, and Free T3. These results help show how well your thyroid is working and whether your levels are in the expected range. We offer a basic thyroid function test that includes all of these markers, as well as more advanced options if you’d like a deeper look at things like thyroid antibodies and overall thyroid health.

What are common thyroid dysfunction symptoms in women?

Women are more likely than men to develop thyroid problems, particularly during times of hormonal change such as pregnancy, perimenopause and menopause.

Common symptoms include tiredness, unexplained weight changes, low mood, anxiety, brain fog, changes in heart rate, and feeling unusually cold or hot. As these symptoms often overlap with hormonal changes, they can be easy to dismiss.

Read our blog on thyroid vs menopause.

What are common thyroid dysfunction symptoms in men?

Men can still develop thyroid problems, even though they’re much more common in women (around 5–10 times more likely).

Symptoms in men can include tiredness, unexplained weight changes, low mood or irritability, brain fog, feeling unusually cold or hot, and changes in heart rate — and they can come on gradually, so it’s easy to put them down to stress, sleep, or getting older.

Can thyroid problems cause weight gain?

Yes. An underactive thyroid (hypothyroidism) can slow your metabolism, which may lead to gradual weight gain and fluid retention. It can also leave you feeling tired and sluggish, so you may move less day to day or feel less motivated to exercise — which can make weight changes more noticeable.

What are normal thyroid levels?

Normal thyroid levels vary depending on the hormone being measured and the laboratory reference range used.

At Medichecks, our Thyroid Function Blood Test measures:

  • TSH (thyroid stimulating hormone)
  • Free T4 (thyroxine)
  • Free T3 (triiodothyronine)

In most UK laboratories, a typical reference range for TSH is approximately 0.4–4.0 mIU/L, although this can vary slightly between labs. Free T4 and Free T3 also have their own specific ranges.

Rather than relying on a single number, thyroid results are interpreted together.

For example:

Every Medichecks thyroid blood test includes a clear results chart showing your levels alongside the laboratory reference range, plus personalised doctor comments to help you understand what your results mean for you.

If you're unsure whether your thyroid levels are normal, testing is the most reliable way to get clarity.

Do I need to fast before a thyroid blood test?

No, you do not usually need to fast before a thyroid blood test.

Thyroid function tests, including TSH, Free T4 and Free T3, are not significantly affected by food, so you can normally eat and drink as usual.

However, there are a few exceptions to keep in mind:

If your test includes additional markers (such as cholesterol or glucose), fasting may be required.

If you take thyroid medication (such as levothyroxine), you may be advised to take your blood sample before your daily dose.

Always follow the specific preparation instructions provided with your test kit.

If you're unsure, check your test instructions or contact our team before taking your sample.

How long do thyroid blood test results take?

With Medichecks, most thyroid test results are ready in around two working days once your sample reaches the lab (you’ll see an estimated turnaround time on each test page, and we’ll email you when your sample arrives and when results are ready).

If you choose the Selenium Blood Test, it can take around seven working days to receive your results.

NHS timings can be different, as tests are usually arranged through your GP and the process can take longer depending on local lab capacity and how results are communicated.

Can thyroid issues cause fatigue?

Thyroid hormone imbalances can affect metabolism and energy regulation. Both underactive and overactive thyroid conditions may be associated with tiredness or low energy.

Should I repeat a thyroid blood test?

Repeat testing may be recommended if results are borderline, symptoms persist, or monitoring is required. Thyroid hormone levels can fluctuate over time.

Can I order a thyroid blood test without seeing a GP?

Yes. Medichecks thyroid blood tests can be ordered directly online, with laboratory analysis and clinician-reviewed reporting included.