Private thyroid function test - Harley Street, London
Comprehensive thyroid blood testing with results in 1-2 days. Three profiles available, from basic screening to a full thyroid panel with antibodies. No referral needed.
Comprehensive
- Up to 6 thyroid markers
- Including antibodies and peroxidase
- Not just TSH
Fast results
- 1-2 working days
- UKAS-accredited laboratory
- GP review available
Accessible
- No referral needed
- Same-day blood draw
- Open 7 days a week
"Your thyroid is fine." But you don't feel fine.
This is the most common thing we hear from patients who book private thyroid testing. Their GP checked TSH, maybe free T4, told them the results were "normal," and sent them on their way. But the fatigue hasn't gone. The weight is still creeping up. The brain fog, the hair thinning, the feeling of being cold all the time: none of it has been explained.
The problem often isn't that your thyroid is fine. The problem is that the test wasn't thorough enough.
The NHS typically tests TSH alone as a first-line screening, and sometimes adds free T4 if TSH is abnormal. That tells you whether your pituitary gland is asking your thyroid to work harder, but it doesn't tell you the whole story. It doesn't measure free T3 (the active hormone your cells actually use), and it doesn't check for thyroid antibodies, which can indicate autoimmune thyroid disease even when TSH and T4 are still within range.
If you want the full picture, you need the full panel.
What is a thyroid function test?
A thyroid function test is a blood test that measures the hormones produced by your thyroid gland and the pituitary hormone (TSH) that controls it, used to diagnose conditions including hypothyroidism (underactive thyroid), hyperthyroidism (overactive thyroid), Hashimoto's thyroiditis, and Graves' disease. A comprehensive thyroid panel includes TSH, free T4, free T3, thyroid antibodies, and thyroid peroxidase antibodies, giving a complete picture of thyroid health rather than the partial view provided by TSH alone.
Why your GP's thyroid test might not be enough
This isn't a criticism of your GP. NHS guidelines are designed for population-level screening, not individual investigation. The standard pathway is:
Step 1: Test TSH. If it's within the reference range (roughly 0.4-4.0 mIU/L), the thyroid is considered "normal."
Step 2: If TSH is abnormal, add free T4.
Step 3: If both are abnormal, refer to endocrinology.
The gap is what happens when your TSH is "normal" but you still have symptoms. A TSH of 3.8 is technically within range, but for many people it's the upper end of their individual normal and they feel it. Your GP probably won't investigate further because the number falls within the reference interval.
A comprehensive private thyroid panel closes that gap:
Free T3 measures the active thyroid hormone. Your body converts T4 into T3, and some people convert poorly. Their T4 and TSH may look fine while their T3 is low, which explains the persistent symptoms.
Thyroid antibodies (anti-TPO and anti-thyroglobulin) detect autoimmune thyroid disease, primarily Hashimoto's thyroiditis. Antibodies can be elevated for years before TSH becomes abnormal. If you have a family history of thyroid disease, this is particularly relevant because antibodies can flag the condition long before standard screening catches it.
Our thyroid profiles
| Service / Marker | Profile 1 | Profile 3 | Profile 2 |
|---|---|---|---|
| Best for | Basic screening | Most patients | Full investigation |
| Markers | FT4, TSH | FT3, FT4, TSH | T4, TSH, FT3, FT4, antibodies, peroxidase |
| Turnaround | 1 working day | 1 working day | 2 working days |
| Price | £100 | £142.50 | £238.75 |
| Includes FT3 | ✗ | ✓ | ✓ |
| Includes antibodies | ✗ | ✗ | ✓ |
| Book | Book - Most popular | Book |
A £50 phlebotomy fee applies to all blood tests, covering your clinical blood draw and sample handling by registered medical professionals.
Not sure which profile? Profile 3 (£142.50) is what most patients choose. It gives you FT3, FT4, and TSH, which is significantly more informative than the standard NHS screening. If you have a family history of thyroid disease, suspect autoimmune thyroid problems, or have been symptomatic for a long time with "normal" results, Profile 2 (£238.75) adds antibodies and peroxidase to the panel.
What each marker tells you
TSH (thyroid-stimulating hormone)
Produced by the pituitary gland, TSH tells your thyroid how much hormone to make. A high TSH suggests your thyroid is underperforming (hypothyroidism); a low TSH suggests it's overactive (hyperthyroidism). TSH is the standard first-line screening test, but on its own it only shows one part of the picture.
Free T4 (thyroxine)
The main hormone produced by the thyroid gland. Most T4 circulates in the blood bound to proteins; "free" T4 is the unbound, active portion. Low free T4 with high TSH confirms hypothyroidism. High free T4 with low TSH confirms hyperthyroidism.
Free T3 (triiodothyronine)
The most metabolically active thyroid hormone. Your body converts T4 into T3, and T3 is what your cells actually use for energy, metabolism, and temperature regulation. Some people convert T4 to T3 poorly, which means their TSH and T4 may look normal while their T3 is low. Only included in Profile 3 and Profile 2.
Thyroid antibodies and peroxidase (anti-TPO, anti-Tg)
These markers detect autoimmune attack on the thyroid gland. Elevated antibodies indicate Hashimoto's thyroiditis (the most common cause of hypothyroidism in the UK) or, less commonly, Graves' disease. Antibodies can be raised years before TSH becomes abnormal. Only included in Profile 2.
Who should consider private thyroid testing?
You've had NHS thyroid tests that came back "normal" but you still have symptoms. Fatigue, weight gain, brain fog, hair thinning, feeling cold, constipation, dry skin, low mood, heavy or irregular periods. If these symptoms persist and your GP has only checked TSH, a more comprehensive panel may reveal what was missed.
You have a family history of thyroid disease. Autoimmune thyroid conditions run in families. If a parent or sibling has hypothyroidism, Hashimoto's, or Graves' disease, antibody testing can detect your risk before symptoms develop.
You're in perimenopause or menopause. Thyroid symptoms overlap significantly with menopausal symptoms (fatigue, weight changes, mood changes, brain fog). It's worth checking whether the thyroid is contributing, particularly as thyroid disease becomes more common with age.
You're on thyroid medication and want to check your levels. If you're already taking levothyroxine or liothyronine and want to monitor your levels privately, any of our profiles can be used for ongoing monitoring. Bring your results to your next GP or endocrinology appointment, or book a GP review with us.
You're experiencing unexplained fatigue, weight changes, or mood changes and want to rule the thyroid in or out as a cause.
Book your thyroid blood test: call 020 7499 1991 or book online. Same-day appointments, 7 days a week. Results in 1-2 days.
How it works
Book your blood test.
No referral needed. Choose your profile online or call us and we'll help you decide. Same-day appointments available seven days a week.
Attend for your blood draw.
A registered medical professional takes your blood sample at 117a Harley Street. The appointment takes approximately 10-15 minutes. No fasting required for thyroid tests.
Laboratory analysis.
Your sample is processed by a UKAS-accredited laboratory. Results are returned in 1 working day for Profiles 1 and 3, or 2 working days for Profile 2.
Receive your results.
Your results are emailed to you with reference ranges so you can see where your levels fall.
GP review (optional).
If you'd like a doctor to interpret your results, explain what they mean, and advise on next steps, book a follow-up consultation (£100) or a full GP appointment (£150). If your results indicate a thyroid condition that needs specialist input, we can refer you directly to an endocrinologist, or you can take your results to your NHS GP.
Pricing
| Test | What's included | Turnaround | Price |
|---|---|---|---|
| Thyroid Profile 1 | FT4, TSH | 1 working day | £100 |
| Thyroid Profile 3 (most popular) | FT3, FT4, TSH | 1 working day | £142.50 |
| Thyroid Profile 2 (comprehensive) | T4, TSH, FT3, FT4, antibodies, peroxidase | 2 working days | £238.75 |
| GP results review | Doctor interprets your results and advises next steps | Same-day or next-day | £100 |
| Full GP consultation | Assessment, examination, prescription if needed | Same-day | £150 |
A £50 phlebotomy fee applies to all blood tests.
CQC registered since 1984. UKAS-accredited laboratory. Same-day blood draw 7 days a week. No referral needed.
Book your private thyroid blood test
Medical Express Clinic, 117a Harley Street, London. Results in 1-2 days.
CQC registered · UKAS-accredited laboratory partners · Open 7 days a week
Treatment Menu & Fees
Transparent pricing for all our services.
Thyroid Profile 1
£100Thyroid Profile 3 (most popular)
£142.50Thyroid Profile 2 (comprehensive)
£238.75GP results review
£100Full GP consultation
£150Common Questions
Q.How much does a private thyroid test cost in the UK?
At Medical Express Clinic, thyroid profiles range from £100 (basic TSH and FT4) to £238.75 (full panel with FT3, antibodies, and peroxidase). A £50 phlebotomy fee applies. Results are returned in 1-2 working days.
Q.Which thyroid profile should I choose?
Most patients choose Profile 3 (£142.50), which includes FT3, FT4, and TSH. This is significantly more comprehensive than the standard NHS screening. If you have a family history of thyroid disease, symptoms that have persisted despite 'normal' NHS results, or suspect an autoimmune thyroid condition, choose Profile 2 (£238.75) which adds antibodies and peroxidase.
Q.My GP says my thyroid is normal. Should I still get tested?
If your GP tested TSH only and your symptoms persist, a more comprehensive panel (including FT3 and antibodies) may reveal what was missed. A 'normal' TSH does not rule out all thyroid problems. Poor T4-to-T3 conversion and early autoimmune thyroid disease can both be present with a normal TSH.
Q.Do I need to fast before a thyroid blood test?
No. Fasting is not required for thyroid testing. However, if you take thyroid medication (levothyroxine), take your dose after the blood draw rather than before, as it can temporarily affect your FT4 reading. If you take biotin supplements (also sold as vitamin B7 or vitamin H, and found in many hair/skin/nail supplements), stop them at least 48 hours before your blood test, as biotin can interfere with some thyroid assays and produce inaccurate results.
Q.What happens if my results are abnormal?
You have two options. You can book a GP review with us (£100 or £150 depending on whether you need a full consultation) and we can advise on treatment or refer you to an endocrinologist directly. Or you can take your results to your NHS GP for further management. We provide your full results with reference ranges either way.
Q.Can I use these results with my NHS GP?
Yes. Your results come from a UKAS-accredited laboratory and are clinically valid. You can share them with your NHS GP, endocrinologist, or any other healthcare provider.
Q.How often should I have my thyroid checked?
If you're asymptomatic with no family history, there's no standard recommendation for routine thyroid screening. If you have known thyroid disease or are on medication, your endocrinologist or GP will advise on monitoring frequency (typically every 6-12 months). If you have a family history of autoimmune thyroid disease, periodic antibody testing is reasonable even if your TSH is currently normal.
Q.I'm already on levothyroxine. Can I use this to monitor my levels?
Yes. Any of our profiles can be used for ongoing monitoring. Take your medication after the blood draw, not before. Profile 3 (including FT3) is recommended for monitoring because it shows whether you're converting T4 to T3 effectively, which TSH and FT4 alone don't reveal.
