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Thyroid Antibody Test
Thyroid peroxidase and thyroglobulin antibodies, the two antibodies that can point to an immune reaction against the thyroid.
- Doctor-reviewed results
- Laboratory analysis
- 1 to 2 working days from lab receipt
- No fasting required
What’s included
2 markers measured
Thyroglobulin antibodies
Another antibody the immune system can make against the thyroid. It is usually read alongside thyroid peroxidase antibodies, the main thyroid antibody test in UK guidance.
Thyroid peroxidase antibodies
Thyroid peroxidase antibodies (TPOAb) are a type of thyroid autoantibody. Raised levels suggest autoimmune disease as the cause of an underactive thyroid. In mildly underactive (subclinical) hypothyroidism, a positive result means a higher chance of progressing to full hypothyroidism. Repeat testing is not usually needed.
Overview
If a TSH has come back slightly raised, a useful next question is whether the immune system is involved, because raised antibodies make it more likely that a borderline result will change over time. This test measures thyroid peroxidase and thyroglobulin antibodies, the two most often measured in autoimmune thyroid conditions. People also choose it when a parent, brother or sister has thyroid disease.
TSH and free T4 say how the thyroid is working today. Antibodies say something different: whether the immune system is involved. When they are raised, a borderline thyroid result is more likely to change over time, which is why UK guidance takes them into account when deciding how often to recheck an untreated, slightly raised TSH. Antibodies are also common in people whose thyroid function is completely normal, so a doctor reads them together with your thyroid hormone levels rather than on their own.
Who this is for and who it isn’t
Who it’s for
- Adults aged 18 and over
- Anyone with a slightly raised TSH who wants to know whether the immune system is involved
- People with thyroid disease in a parent, brother or sister
Who it isn’t for
- This is not a thyroid function test and it will not tell you whether your thyroid is working. TSH and free T4 do that, and if you have not had them, the Thyroid Check is the right starting point. Antibodies can also be found in people whose thyroid works normally, so a positive result on its own is not a condition.
- Repeating antibodies is not usually needed, because follow-up is guided by your thyroid hormone levels.
- Anyone with a new, severe or worsening symptom: contact your GP or call NHS 111. A test you buy today is not a substitute for being examined.
Common reasons people choose this test
- A previous TSH result that was slightly outside the range
- Thyroid disease in a parent, brother or sister
- Tiredness, feeling cold or weight change alongside a known thyroid result
- Planning a pregnancy, if a doctor has suggested a thyroid check
These are reasons people choose to test, not signs that something is wrong. A result is one part of a picture your doctor puts together with your history and an examination.
What your result looks like
Every result is shown with the unit and the reference range exactly as the laboratory reported it, with the doctor’s note underneath.
- Thyroglobulin antibodiesIn range
- Result
- 20 IU/mL
- Range
- <115
- Thyroid peroxidase antibodies▲ High
- Result
- 180 IU/mL
- Range
- <34
| Marker | Result | Units | Range | Flag |
|---|---|---|---|---|
| Thyroglobulin antibodies | 20 | IU/mL | <115 | In range |
| Thyroid peroxidase antibodies | 180 | IU/mL | <34 | ▲ High |
Doctor’s note (example)
Thyroid peroxidase antibodies are positive, which can be consistent with autoimmune activity against the thyroid. With a normal TSH a clinician may recommend nothing more than a yearly TSH to keep an eye on it.
Values above are examples. Your report shows your own results with the laboratory’s units and reference range for your age and sex, reviewed, signed and released by a GMC-registered doctor.
How it works
- Your kit arrivesPosted to your door, with instructions and what you need to send your sample back.
- You take your sampleFinger-prick sample at home, or a clinic blood draw, your choice
- The laboratory analyses itYour sample is processed for the measurements included in this test. Lab processing typically takes 1 to 2 working days from receipt of your sample.
- A doctor reviews and releases itA GMC-registered doctor reads every result and signs the report before it reaches you.
- Sample
- Home finger-prick kit
- Preparation
- No fasting required
- Who it's for
- Any sex · ages 18+
How to prepare
What we can and can’t tell you
The reference range beside each result is the laboratory’s own. A result in range is not a clean bill of health and a result outside it is not a diagnosis. Most ranges cover about 95% of healthy people, so about 1 in 20 healthy people fall just outside any one range. No test result replaces an examination or your own doctor’s judgement, and none of these panels is a cancer screening programme.
Read the full note
The reference range printed beside each of your results is the laboratory's own, and it is the range that applies to your result. We do not apply a second range of our own, and we do not tell you that a result the laboratory reported as normal is nonetheless too low or too high. If you see a claim elsewhere that your result ought to sit inside a narrower band than the one the laboratory printed, treat it with caution and ask your doctor.
Some assays cannot give an exact figure above or below a certain point, and those results are reported the way the laboratory sends them, for example as a value greater than a stated number. A result in range is not a clean bill of health, and a result outside a range is not a diagnosis: most reference ranges are set to cover about 95% of healthy people, so some healthy people fall just outside them. No blood test replaces an examination, a scan or your own doctor's judgement, and none of these panels is a screening programme for cancer.
If you have a symptom that is new, severe, or getting worse, contact your GP or NHS 111 rather than waiting for a test result. In an emergency call 999.
Frequently asked questions
What is the difference between the two antibodies?
Thyroid peroxidase antibodies are the ones most often measured. This test reports thyroglobulin antibodies alongside them.
I have antibodies but my thyroid is normal. What now?
That is a common combination and for many people nothing changes. Whether and how often to recheck your thyroid function is something to agree with your GP, and the doctor's note explains your own results.
Should I have TSH as well?
Ideally yes, because antibodies only mean something alongside thyroid function. If you have not had a recent TSH and free T4, the Thyroid Check or the Advanced Thyroid Check with Antibodies covers both in one sample.
Does the day or time matter?
No fasting is needed for this test.
How long do results take?
The laboratory typically takes 1 to 2 working days from receiving your sample. This does not include kit delivery, sample collection or return postage. A doctor reviews your results before they are released.
Can I choose a home kit or a clinic?
Both, it is your choice at checkout. Either collect a finger-prick sample at home with the posted kit and send it back as the instructions explain, or book a clinic appointment and have a trained clinician take the sample for you.
Is a doctor involved?
Yes. Every result is reviewed by a GMC-registered doctor who signs it off and explains what it means and what to do next.
Is it confidential?
Your results are available through your secure patient portal. Our privacy policy explains how your information is handled and when it may be shared to provide your care.
What happens to my sample and results?
Your sample is analysed at a UKAS-accredited laboratory (ISO 15189). A GMC-registered doctor then reads every result and signs the report before it is released, so nothing reaches you unreviewed. There is no option to receive results without a doctor reading them first. The report arrives in your secure portal in plain English: each result with its unit and the laboratory's own reference range, and the doctor's note on what the set means read together. If a result sits outside its range the report says so and explains what usually happens next, which is most often a conversation with your own GP, who can act on it alongside your history and examination. Most reference ranges are set to cover about 95% of healthy people, so about 1 in 20 healthy people fall just outside any one of them. On a report with many results it is common for one to sit just outside its range, and a single number on its own rarely tells the whole story. If a result needs urgent attention, the reviewing doctor is alerted straight away and we contact you by phone the same working day rather than leaving it in the portal for you to find. If a specific result needs rechecking, the reviewing doctor says so in your report.
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