Private Free T3 Test (Triiodothyronine) Test in the City of London
Measure Free T3 - the most active thyroid hormone that directly affects metabolism and energy.
2 min from St Paul's station · short walk from Bank, Blackfriars & Barbican
Free T3 (Venous)
Test fee £63 + £50 phlebotomy fee (per visit)
- Results in 1 day"
- UKAS accredited laboratory
- Professional phlebotomy service
- Confidential results portal
Or call 020 7183 3709
Pay at clinic on the day of your appointment
The Free T3 (Venous) is available privately at our clinic in The City of London for £63.
* Excluding £50 phlebotomy fee (per visit)
The thyroid is a butterfly-shaped gland located in the front of the neck. It produces hormones that regulate metabolism, energy levels, heart rate, body temperature, and mood. Even small changes in thyroid function can have a noticeable impact on how you feel day to day.
Thyroid conditions are common in the UK, particularly among women and those over 40. Conditions such as hypothyroidism (underactive thyroid) and hyperthyroidism (overactive thyroid) can develop gradually, and symptoms may be attributed to other causes before a diagnosis is made.
What the Free T3 (Venous) Measures
- TSH (thyroid-stimulating hormone) — the primary marker used to assess thyroid function
- Free T4 (thyroxine) — the main hormone produced by the thyroid gland
- Free T3 (triiodothyronine) — the active form of thyroid hormone used by the body
When This Test May Be Helpful
- Unexplained fatigue, tiredness, or low energy levels
- Unexplained weight gain or difficulty losing weight
- Feeling unusually cold or sensitive to temperature changes
- Changes in mood, including low mood or anxiety
- Changes in hair, skin, or nails
- A family history of thyroid conditions
- Monitoring an existing thyroid condition or medication
Preparation Before Your Test
No fasting is required for thyroid blood tests. However, if you take thyroid medication (such as levothyroxine), it is usually recommended that you take your blood sample before your morning dose.
If you are unsure about timing around medication, discuss this with your prescribing clinician before your appointment.
Understanding Your Results
Results for this test are typically available within 1 day". They are delivered securely and confidentially.
Your results will show whether your thyroid hormone levels fall within the expected reference range for your age and sex. Values outside the normal range may indicate an underactive or overactive thyroid, but this depends on the clinical context.
If your results are abnormal or you have concerns, we recommend sharing them with your GP, who can provide clinical interpretation and advise on any further steps, including treatment if appropriate.
Important Information
This test provides laboratory results only. It does not include clinical interpretation, diagnosis, or treatment recommendations. If your results are outside the normal range, please consult your GP for further advice.
Check Active Thyroid Hormone
T3 is the active form of thyroid hormone - some people convert T4 poorly and benefit from T3 testing.
- Active hormone assessment
- Conversion issues
- Persistent symptoms
- T3 toxicosis detection
- Medication optimisation
- Complete thyroid picture
How It Works
Book Online
Choose a convenient date and time
Visit Our Clinic
Ave Maria Lane, City of London
Quick Blood Draw
Professional phlebotomy - 5 minutes
Get Results
Results in 1 day"
Frequently Asked Questions
Common questions about this blood test
Visit Our London Clinic
Central London location with excellent transport links
Address
St Paul's Medical & Dental
Ave Maria Lane
The City of London
London EC4M 7AQ
Getting Here
- Walking distance from St Pauls, Blackfriars, Bank and Barbican stations
- Circle, District & Piccadilly lines
Opening Hours
Current opening hours:
- Monday – Friday8am–6pm (Fri until 2pm)
- SaturdayClosed
- SundayClosed
Contact
Ready to Book Your Test?
No GP referral needed. Book online and get tested at our City of London clinic. Results within 1 day".
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Related Tests
Thyroid Profile 1
Essential thyroid function check including TSH and Free T4.
TSH Test
Thyroid-stimulating hormone test for thyroid function screening.
Free T4 Test
Active thyroid hormone measurement for thyroid function.
Thyroid Profile 2
Extended thyroid panel including TSH, Free T4, and thyroid antibodies.
Patient Reviews
Read patient feedback and see why professionals and families across the City choose our clinic.
We look forward to providing exceptional dental and medical care to the City of London community.
Meet Our Medical Team
Our experienced medical team is fully qualified and registered with the GMC and NMC, delivering safe, high-quality care in line with the highest professional standards.
Because our patients deserve nothing less.
Registered. Regulated. Trusted.
At St Paul's Medical & Dental, we are registered with the Care Quality Commission (CQC) as Medical and Dental Limited (Provider ID: 1-29171948282), and our clinicians are registered with the relevant UK regulatory bodies, including the GDC and GMC. Our dentists, dental nurses and medical professionals deliver care that meets the highest clinical, safety and ethical standards, because our patients deserve nothing less.
Visit us at St Paul's
Private blood tests beside St Paul’s Cathedral — 2 minutes from St Paul’s tube and a short walk from Bank, Blackfriars and Barbican. Early appointments from 8am.
5 Ave Maria Lane, The City of London, EC4M 7AQ
We Accept All Major Dental Insurances
Use your workplace or personal dental cover with us. We provide itemised receipts and completed claim forms for all major UK insurers — including AXA Health, Aviva, Bupa, Cigna, Vitality, Westfield Health, WPA, Unum, and Boots Dental Plan.
You pay for treatment at the clinic and claim reimbursement from your insurer. Cover levels vary by policy — check your plan details. All insurer names and trademarks belong to their respective owners.