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Frequently Asked Questions About Thyroid Tests

 Here are some of the most frequently asked questions. If you need anything else try our help section.

  • What does the hormone TSH do?

    Thyroid stimulating hormone (TSH) is produced by the pituitary gland and acts on the thyroid to stimulate it to produce the hormones thyroxine and triiodothyronine.

  • What is an overactive thyroid?

    An overactive thyroid, also known as hyperthyroidism,  means you have too much thyroid hormone acting on the cells in your body which speeds them up. Their increased function can cause a variety of symptoms, such as anxiety, fast heartbeat, weight loss, sleep disturbances, trembling, and excessive sweating.

  • What autoimmune conditions can cause thyroid disorders?

    Thyroid conditions can be caused by autoimmune diseases where your immune system mistakenly attacks its own cells resulting in an immune response and some unpleasant symptoms.

    Graves’ disease, for example, causes hyperthyroidism or an overactive thyroid. Because your immune cells attack the thyroid, it causes it to produce more thyroid hormones than your cells need and speeds up the rate at which they work. Whereas Hashimoto’s disease is an autoimmune condition that causes an underactive thyroid (hypothyroidism). It occurs when your immune system attacks the thyroid causing damage which results in not enough thyroid hormones being produced and slowing down your cells’ metabolism.

  • How do you test your thyroid function at home?

    Our thyroid blood test can be done easily at home using our finger prick test kit. 

    The kit contains everything you need to do the thyroid test at home and to send your sample to our UKAS accredited lab here in the UK.

    The kit contains:

    • Test tube/s
    • 3/4 lancets
    • Sterilising wipes
    • Plasters
    • Lab request form with labels
    • Plastic case to protect your sample in transit to the lab
    • Tracked-24 prepaid return envelope
  • Are thyroid test accurate

    We’ve conducted independent research to ensure our capillary collection and testing processes for all our tests, including our thyroid blood test, are an accurate blood collection method and compare with the tests that your GP would carry out.

    Learn more about our test accuracy.

  • What is triiodothyronine?

    Triiodothyronine, also known as T3, is a hormone produced by your thyroid and affects nearly all of the processes in the body. It helps to regulate your metabolism, so how fast or
    slow your cells work.

  • What is an underactive thyroid?

    An underactive thyroid is also known as hypothyroidism and is caused by a lack of thyroid hormones. Because there aren’t enough thyroid hormones being made, the activity of your cells slows down and causes symptoms such as weight gain, low mood, and forgetfulness.

  • What are thyroid levels supposed to be?

    Normal levels of thyroid hormones and antibodies are:

    • Thyroid stimulating hormone – 0.27-4.2 mIU/L
    • Thyroxine (FT4) – 12-22 pmol/L
    • Triiodothyronine (FT3) – 3.1 – 6.8 pmol/L

    Please note reference ranges can vary by lab and analytical process.

  • What thyroid test is best?

    A thyroid test that measures the level of thyroid hormones and antibodies from a blood sample analysed by a lab is best.

    Measuring both thyroid hormones and antibodies can help identify thyroid and autoimmune conditions.

    A thyroid test should measure:

    1. Thyroid stimulating hormone
    2. Thyroxine (T4)
    3. Triiodothyronine (T3)
    4. Thyroglobulin antibodies
    5. Thyroid peroxidase antibodies
  • Why is a thyroid test is done?

    A thyroid test is carried out when a thyroid condition is suspected based on symptoms. 

    Symptoms of a thyroid disorder include:

    • Feeling nervous, anxious, or irritable
    • Mood changes
    • Difficulty sleeping
    • Fatigue
    • Muscle weakness
    • Itchiness
    • Hyperactivity
    • Sensitivity to heat
    • Weight gain
    • Constipation
    • Depression
    • Dry skin
    • Low sex drive
    • Sensitivity to cold
    • Slow movements and thoughts
    • Brittle hair and nails
    • Irregular or heavy periods

    Learn more about why you should test your thyroid function.