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Add a report from your GP, the NHS App or a clinic, and see your results, medicine and how you feel over time. We explain each level in plain words, read against the lab’s own range. Members watch these films in the app, beside their own results.
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The film in words
The thyroid is a small gland at the front of the neck, just below the Adam’s apple. It has two lobes, one on each side of the windpipe, joined by a small bridge of tissue.
It makes two hormones, T4 and T3. They set the speed the body’s cells work at, and affect everything from heart rate, circulation and bones to how you think and feel.
T4 is the main hormone the thyroid makes. The test measures the “free” part, which the body can use.
The body turns T4 into T3, the form it actually uses. Free T3 is usually only tested to check for an overactive thyroid, or how overactive it is.
TSH is a hormone from a small gland at the base of the brain. It tells the thyroid how much hormone to make. When thyroid hormone is low, TSH goes up. When it’s high, TSH goes down.
If the thyroid makes too little hormone, the body’s cells and organs slow down. This is an underactive thyroid (hypothyroidism), the most common thyroid disorder.
Sources: British Thyroid Foundation: your thyroid gland; British Thyroid Foundation: thyroid function tests
More films
What your blood test showsWhat a usual test looks at, TSH and free T4 side by side, and lab ranges.1 min 31
Hashimoto’s: why the thyroid slows downThe immune system, TPO antibodies, and why the test isn’t repeated.1 min 04
Levothyroxine, and how to take itWhat it does, taking it so it’s absorbed, missed doses, and why changes take time.1 min 41
Still not feeling right?When results are in range but symptoms aren’t, and what to ask your GP.1 min 16
Basic and full thyroid testsWhat TSH, free T4, free T3 and the two antibodies each add.1 min 33
Lab ranges and your reportThe units on a report, typical ranges as a guide, age, and antibody cut-offs.1 min 17
TPO antibodies, in detailWhat a positive result can mean, with or without a thyroid problem, and why it stays.1 min 11
Tg antibodies, in detailThyroglobulin, why it’s watched after thyroid cancer, and what its antibodies change.58 sec
Iron, B12 and vitamin DOther results you may have, why they come up with the thyroid, and coeliac disease.1 min 25
Pregnancy and your thyroidPlanning a pregnancy, the dose and tests in pregnancy, and after the birth.1 min 33
General information, not a diagnosis. Your GP can tell you what your results mean for you.