Thyroid Stimulating Hormone
The TSH blood test measures thyroid stimulating hormone to assess how well the thyroid is regulated. It is the primary test used for diagnosing and monitoring thyroid conditions.
Turnaround time
2 days
Biomarkers count
1
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Details about Thyroid Stimulating Hormone
What is the Thyroid Stimulating Hormone test?
The Thyroid Stimulating Hormone (TSH) test measures the level of TSH produced by the pituitary gland. TSH acts as a control signal, telling the thyroid gland how much thyroid hormone to produce.
When thyroid hormone levels fall, TSH rises to stimulate production. When thyroid hormone levels are high, TSH falls. This feedback loop makes TSH a sensitive indicator of thyroid function and regulation.
The test is widely used as a first-line assessment of thyroid health and for ongoing monitoring of thyroid treatment.
Why do I need a TSH test?
Abnormal TSH levels often appear before changes in thyroid hormones, making this test essential for early detection and monitoring of thyroid disorders.
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 or low mood
- Irregular menstrual cycles
- Known thyroid condition requiring monitoring
- Follow-up after thyroid medication changes
The test helps determine whether symptoms are linked to thyroid regulation rather than thyroid hormone production alone.
Benefits of the test
- Primary thyroid screening tool
Most sensitive first-line test for thyroid dysfunction. - Detects early thyroid imbalance
Abnormal TSH often appears before hormone changes. - Essential for treatment monitoring
Tracks response to thyroid medication. - Guides further testing
Indicates when Free T4, Free T3, or antibody tests are needed. - Supports safe dose adjustment
Helps prevent over- or under-treatment. - Simple blood-based testing
Requires only one blood sample. - Widely clinically accepted
Standard test used across UK healthcare. - Useful across all ages
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
High TSH (suggestive of underactive thyroid)
- Elevated TSH level
- UK standard (typical): >4.5 mIU/L
- May indicate hypothyroidism or inadequate thyroid hormone levels
Normal TSH
- TSH within reference range
- UK standard (typical): 0.4–4.0 mIU/L
- Suggests normal thyroid regulation
Low TSH (suggestive of overactive thyroid)
- Suppressed TSH level
- UK standard (typical): <0.1 mIU/L
- May indicate hyperthyroidism or excessive thyroid hormone levels
How It Works
Simple steps to get your results
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Choose your test online and book in seconds. Select your preferred clinic location or home visit option.
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.
Get Your Results
Your sample is analysed by accredited UK laboratories, with secure results delivered directly to you.
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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.