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Thyroid Function - Diagnosis and Monitoring
49.00
This thyroid function test assesses how well the thyroid gland is working. It is used for diagnosis, treatment monitoring, and long-term thyroid health management.
Turnaround time
2 days
Biomarkers count
5
Same-Day Appointments
UKAS Accredited Labs
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Under 18? Patients under 18 can only be seen at GB Medlabs and Clinilabs, Monday to Friday only.
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Details about Thyroid Function - Diagnosis and Monitoring
What is the Thyroid Function – Diagnosis and Monitoring test?
The Thyroid Function – Diagnosis and Monitoring test is a blood test designed to assess how effectively the thyroid gland is producing and regulating thyroid hormones. These hormones play a central role in metabolism, energy production, temperature regulation, and overall wellbeing.
The test focuses on measuring key thyroid hormones and regulatory signals to determine whether the thyroid is underactive, overactive, or functioning normally. It is commonly used both at initial diagnosis and during ongoing monitoring of known thyroid conditions.
This test is essential for tracking disease progression and evaluating how well treatment is working over time.
Why do I need a Thyroid Function test?
Thyroid disorders often cause broad, non-specific symptoms that can mimic other health issues. Regular testing is crucial for accurate diagnosis and safe monitoring once treatment has started.
You may need this test if you experience:
- Persistent fatigue or low energy
- Weight gain or weight loss
- Cold or heat intolerance
- Hair thinning or hair loss
- Palpitations or irregular heartbeat
- Anxiety, low mood, or brain fog
- Changes in appetite
- Known thyroid disease requiring monitoring
- Medication dose adjustment or follow-up
Ongoing monitoring helps ensure thyroid hormone levels remain within a safe and effective range.
Benefits of the test
- Supports accurate diagnosis
Identifies underactive or overactive thyroid patterns. - Essential for treatment monitoring
Tracks response to thyroid medication over time. - Helps optimise medication dosing
Ensures hormone levels stay within target range. - Explains persistent symptoms
Identifies hormonal causes of ongoing symptoms. - Prevents over- or under-treatment
Reduces risks linked to incorrect hormone dosing. - Useful for long-term management
Supports safe, ongoing thyroid care. - Simple blood-based testing
Requires only a blood sample. - Applicable across age groups
Suitable for adults and older individuals.
Step-by-step: How we offer testing
Clinic-based testing (UK-wide)
- Choose your nearest UK clinic
- Attend your appointment
- A clinician draws a blood sample
- Sample is sent to the laboratory
- Results are issued once analysis is complete
Home or hotel visit (+£60, UK-wide)
- Book a mobile phlebotomist
- Blood sample taken at your home or hotel
- No need to attend a clinic
- Sample securely transported to the laboratory
Your results explained
Underactive thyroid (hypothyroid pattern)
- Elevated TSH with low thyroid hormone levels
- UK standards (typical):
- TSH: >4.5 mIU/L
- Free T4: <10 pmol/L
- May be linked to fatigue, weight gain, and cold intolerance
Normal thyroid function (euthyroid)
- TSH and thyroid hormones within reference range
- UK standards (typical):
- TSH: 0.4–4.0 mIU/L
- Free T4: 10–22 pmol/L
- Indicates balanced thyroid regulation
Overactive thyroid (hyperthyroid pattern)
- Suppressed TSH with raised thyroid hormone levels
- UK standards (typical):
- TSH: <0.1 mIU/L
- Free T4: >22 pmol/L
- May be associated with palpitations, anxiety, and heat intolerance
Results should always be interpreted in the context of symptoms and clinical history.
How It Works
Simple steps to get your results
1
Book Online
Choose your test online and book in seconds. Select your preferred clinic location or home visit option.
2
Visit or Test at Home
Attend one of our UK or London clinics, arrange a home nurse visit, or use a finger-prick kit where available.
3
Get Your Results
Your sample is analysed by accredited UK laboratories, with secure results delivered directly to you.
Take control of your health with London Blood Tests
WhatsApp UsHow to Prepare for Your Test
Follow these guidelines for accurate results
Sample Timing
Where possible, attend your blood test between 7am and 12pm. Please wait until any short-term illness or infection has fully resolved before testing. Avoid intense exercise for 24–48 hours beforehand, as this can affect certain markers.
Fasting & Hydration
Fasting is not always required, but some tests may recommend it. If fasting is advised, avoid food for 8–12 hours before your appointment and drink water only. Stay well hydrated, as this helps with sample collection and accuracy.
Medications & Supplements
Continue prescribed medications unless advised otherwise by your clinician. Avoid vitamin, mineral, or biotin supplements for at least 24–48 hours before your test, as these can interfere with results. If you are unsure about any medication or supplement, please let us know before your appointment.
Hormones & Menstrual Cycle
For hormone-related tests, timing within your menstrual cycle may be important. If relevant, follow any specific guidance provided on your test page.
If you have any questions or special circumstances, our team is happy to advise before your appointment.
Frequently Asked Questions
Diagnosis identifies thyroid disease, while monitoring tracks treatment response.
Yes, it is essential for ongoing dose adjustment.
Yes, symptoms may have other contributing factors.
Frequency depends on diagnosis, treatment stage, and stability.
Stress can influence thyroid hormone regulation.
Yes, it applies to both conditions.
Yes, especially during treatment changes.
Yes, thyroid dysfunction is common with ageing.
Not always; early or fluctuating disease may still exist.
It indicates altered thyroid hormone regulation and supports further medical evaluation.
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