What is the thyroid, and why does it matter?
A Thyroid blood test checks how well your Thyroid is working. Depending on which option you choose below, that can mean TSH on its own, TSH and Free T4 together, or our most complete option, Advanced Thyroid, which measures TSH, Free T4, Free T3, and both Thyroid antibody markers. Our private Thyroid blood test requires no referral and is ideal if you’re experiencing unexplained fatigue, weight changes, or mood swings that might be related to Thyroid function.
Why this test matters
The Thyroid is one of the most underdiagnosed glands in the body. Many people suffer from Thyroid dysfunction for months or even years without realising it – sometimes their GP hasn’t checked Thyroid function, or initial tests show results within the “normal range” that are actually suboptimal for them personally. This test gives you a complete picture of Thyroid health and helps identify conditions like hypothyroidism (underactive Thyroid) or hyperthyroidism (overactive Thyroid) early.
No referral needed. Book directly with us and get answers without waiting to see your GP first. Your clinician will review your results in plain English and explain what they mean for you.
What this test measures
Our most complete option, Advanced Thyroid, measures five key markers of Thyroid function.
| Marker | What it measures | Why it matters |
|---|---|---|
| TSH (Thyroid stimulating hormone) | How much your pituitary gland is pushing your Thyroid to produce hormones | The primary screening test for Thyroid disease. High TSH usually means underactive Thyroid; low TSH usually means overactive Thyroid or over-replacement with Thyroid medication. |
| Free T4 | The amount of available thyroxine hormone circulating in your blood | Shows how much active Thyroid hormone your body can actually use. Some people have normal TSH but low Free T4, which explains their symptoms. |
| Free T3 | The amount of available T3 (the active form of Thyroid hormone) | The most biologically active Thyroid hormone. Low Free T3 can cause fatigue and depression even when TSH and Free T4 are normal. Some people don’t convert T4 to T3 efficiently. |
| Thyroid Peroxidase Antibodies | Immune markers that indicate autoimmune Thyroid disease | High Thyroid Peroxidase Antibodies suggest Hashimoto’s disease or Graves’ disease. This explains why your immune system is attacking your Thyroid. |
| Thyroglobulin Antibody | Another immune marker linked to autoimmune Thyroid disease | Often raised alongside Thyroid Peroxidase Antibodies in Hashimoto’s disease. Checking both gives a fuller autoimmune picture than either alone. |
Who should get this test?
A Thyroid blood test is recommended for anyone experiencing symptoms that might be Thyroid-related, or if you have risk factors for Thyroid disease. It’s also essential if you’re already on Thyroid medication and want to check your dose is optimal.
- Persistent fatigue
- Unexplained weight gain
- Unexplained weight loss
- Hair thinning or loss
- Feeling unusually cold
- Feeling unusually hot
- Low mood or depression
- Heart palpitations
- Constipation or diarrhoea
- Family history of Thyroid disease
Which Thyroid test do you need?
Not everyone needs all three markers. If you’re already on Thyroid medication and just need your level checked, or a specific marker has been requested, a smaller test may be all that’s necessary. Here’s how the three options compare.
| Test | What it includes | Best for | Price |
|---|---|---|---|
| TSH Only | TSH | Straightforward monitoring once you’re already on Thyroid medication and stable | £60 |
| Thyroid Profile | TSH and Free T4 | The most commonly requested Thyroid test, and a sensible first check for most people | £65 |
| Advanced Thyroid | TSH, Free T4, Free T3, Thyroid Peroxidase Antibodies and Thyroglobulin Antibody | Our most complete option: adds Free T3 plus both Thyroid antibody tests, useful for ongoing symptoms despite a normal TSH and Free T4, or a family history of autoimmune Thyroid disease | £95 |
Not sure which one? Tell us your situation when you book, or contact us first, and we’ll recommend the right test rather than the most expensive one.
What your results mean
Your results will be presented as numbers alongside reference ranges – the “normal” values for your laboratory. However, “normal” isn’t always “optimal.” Someone with a TSH of 3.5 might be within range but still symptomatic. Our clinician explains what your specific numbers mean in the context of your symptoms, not just whether they fall within a range.
If your results indicate Thyroid dysfunction, we’ll discuss next steps with you. This might include referral to an endocrinologist, prescription of Thyroid medication, repeat testing after dose adjustment, or lifestyle changes that support Thyroid health.
Important: Thyroid medication and certain supplements can affect results. If you’re taking Thyroid medication, the test should be done 6-8 weeks after any dose change. Don’t take biotin supplements for 48 hours before the test as they can interfere with measurements.
What happens at your appointment
When you arrive at our Estover clinic in Plymouth, you’ll be seen by a trained phlebotomist who will take a blood sample – usually less than five minutes. You can eat and drink normally before this test, as it doesn’t require fasting.
Your samples are sent to our laboratory and results are returned the next working day. You’ll receive your results by email as standard, and a follow-up appointment is available if you’d like a clinician to discuss them with you in detail.
Frequently asked questions
What’s the difference between TSH Only, Thyroid Profile and Advanced Thyroid?
TSH Only (£60) checks a single marker – the one most GPs use to monitor someone already on Thyroid medication. Thyroid Profile (£65) adds Free T4, giving a clearer picture for a first check. Advanced Thyroid (£95) adds Free T3 plus both Thyroid antibody tests (Thyroid Peroxidase Antibodies and Thyroglobulin Antibody), useful if you still have symptoms despite normal TSH and Free T4, or there’s a family history of autoimmune Thyroid disease. If you’re not sure which applies to you, ask us when you book.
Do I need to fast before a Thyroid blood test?
No, fasting is not required for a Thyroid blood test. You can eat and drink normally before your appointment. However, try to take the test at a similar time each day if you’re having repeat tests, as Thyroid hormone levels can vary slightly throughout the day.
Can I take my Thyroid medication before the test?
If you’re already on Thyroid medication, take it as normal on the morning of your test – this shows how your current dose is working. However, if you’ve just started or changed your dose, wait 6-8 weeks before testing so your body has time to adjust and levels stabilise.
What does a normal TSH range mean?
TSH typically ranges from 0.4-4.0 mIU/L, but this varies by laboratory. A TSH in the “normal range” doesn’t necessarily mean you’re healthy – many people feel symptomatic with a TSH above 2.5, especially if they have other symptoms. Our clinician considers your full picture, not just the numbers.
Will you test for Thyroid antibodies?
Yes. Both Thyroid antibody tests – Thyroid Peroxidase Antibodies and Thyroglobulin Antibody – are included as standard in Advanced Thyroid (£95), alongside TSH, Free T4 and Free T3. They’re not included in TSH Only or Thyroid Profile, so if antibody testing matters to you – for example a family history of autoimmune Thyroid disease, or symptoms suggesting Hashimoto’s or Graves’ disease – Advanced Thyroid is the one to book. Discuss this with our clinician if you’re unsure.
How often should I have my Thyroid tested?
If you have no symptoms and no family history, once every 5 years is reasonable. If you’re on Thyroid medication, annual testing is standard. If you’re experiencing ongoing symptoms despite treatment, repeat testing 6-8 weeks after any dose change helps find your optimal dose.
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Book your Thyroid blood test in Plymouth
From £60, depending on which test you need. Results next working day. No GP referral needed.
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