NHS App test results explained
Thyroid function test (TFT) results explained
Thyroid function tests show how well your thyroid gland is working. They are used to look for an underactive or overactive thyroid and to check how treatment is going. Most often the result you see first is TSH, the hormone that tells the thyroid how hard to work.
Also printed as: TFT, TFTs, TSH.
What is on the report
Typical adult ranges. Each lab sets its own, so the range printed next to your result is the one that counts.
| Test | What it is | Typical range |
|---|---|---|
| TSH | A brain hormone that tells the thyroid how hard to work. | 0.3–4.2 mIU/L |
| Free T4 | The active, unattached form of the thyroid's main hormone. | 12–22 pmol/L |
| Free T3 | The unattached form of T3, the most active thyroid hormone. | 3.1–6.8 pmol/L |
| TPO antibodies | Immune proteins aimed at an enzyme inside the thyroid. | under 9 IU/mL |
Good to know in United Kingdom
- Many UK laboratories use a cascade. TSH is measured first. If it is above the range, free T4 is added. If it is below the range, free T4 and free T3 are added. So not every report shows all three.
- TSH is reported in mU/L. Free T4 and free T3 are reported in pmol/L.
- Reference ranges vary between laboratories. Pregnancy and young children have different ranges.
- Thyroid antibody tests, such as TPO antibodies, are not part of every TFT. They may be added when an autoimmune thyroid condition is suspected.
Call 999 in an emergency. For urgent advice that is not an emergency, use NHS 111 online or call 111. For questions about your test results, contact your GP surgery.
Keep your reports in one place
Take a photo or screenshot of your results, or upload the PDF, and Vita explains each number in plain words, suggests what to ask your GP, and keeps it with your past results. Vita does not connect to the NHS App or to any UK health record system, and its hospital connections are for US hospitals, not UK ones.
Vita Health Coach on the App StoreAsk it in ChatGPT
Vita Health Coach also answers in ChatGPT. One tap opens ChatGPT with this question ready to send:
“What should I ask the doctor about my Thyroid function tests (TFTs) result?”
Questions
Why was just my TSH tested?
If TSH is normal, the thyroid is very likely working normally, so many labs stop there. They add free T4, and sometimes free T3, when TSH is outside the range.
What can affect thyroid results?
Serious illness, thyroid treatment, some other medicines, and vitamin or mineral supplements, especially those containing iodine or biotin. Tell the person taking your blood about everything you take.
How often are thyroid tests repeated?
Tests are usually more frequent at the start of treatment. Once things are stable, people with an underactive thyroid often have a TSH test once a year, or as their doctor advises.
More for United Kingdom
Sources
General information, not medical advice. VitaMedas is not connected with any government health service. Vita Health Coach explains; it never diagnoses. In an emergency, call 999. Read the medical disclaimer.