There are various tests available for the diagnosis of thyroid disease including thyroid stimulating hormone (TSH); Free T4 (Free thyroxine); Free T3 (Free tri-iodothyronine); thyroid peroxidase antibody (TPO) and thyroglobulin antibody (TgAb).
NHS clinicians in the UK generally test for TSH to diagnose thyroid disease although in some areas of the country, the FT4 is tested too.
Some clinicians test for thyroid antibodies but many feel that this is not necessary.
Testing for FT3 to diagnose hypothyroidism is very rarely undertaken.
Once a patient starts on treatment, NICE guidance states that clinicians should aim to maintain TSH levels within the reference range and that the TSH should be measured every three months until the level has stabilised. After that, testing should be undertaken annually although many patients do not feel that this is often enough.
NICE also state that FT4 should be measured if the patient continues to have symptoms. However, FT4 testing is not always carried out.
FT3 testing is very rarely carried out because it is felt that it is not necessary and it is controversial. In some instances, often when the patient has requested it, the clinician would like to test the FT3 but the local Clinical Commissioning Guidance is that it should not be tested. However – you can’t tell if a patient is converting their thyroxine effectively without an FT3 test.
We know that in other countries all the thyroid tests are carried out including ultrasound testing and for a lot of patients, this would be the ideal in order that a firm diagnosis is made, including whether they have Hashimoto’s disease.
There is, however, more interest now from some researchers and clinicians in patients who do not resolve all of their symptoms on levothyroxine, and more research into combination treatment of levothyroxine and liothyronine is planned (a recommendation from NICE in the Guidance for Thyroid Disease – https://www.nice.org.uk/guidance/ng145/chapter/Recommendations-for-research). There is a consensus document due to be published where a list of research topics regarding liothyronine was discussed.
There has been a move over the past few years towards patients and clinicians sharing the responsibility for their own health – https://www.kingsfund.org.uk/publications/shared-responsibility-health – particularly if they have a long term condition.
To enable this to happen patients need to take control of their health and this includes learning more about their condition, making sure that they take their medication correctly and monitoring their own health.
If a patient wants to monitor their thyroid health more frequently than their clinician or if a particular test is not available on the NHS, they have two options open to them – either visit a private clinician, which can be expensive, or organise private testing for themselves. Until FT3 testing becomes standard in the NHS, and we believe it will, patients may want to check their own levels by self testing.
Thyroid UK also firmly believes that patients should make healthy choices in respect of their diet not only regarding obesity but in respect of nutrition, especially since obesity has been shown to cause a worse COVID-19 outcome.
Poor nutrition is not only a cause of obesity. It can also impact on thyroid health and we see many people with vitamin and mineral deficiencies that could be causing low levels of thyroid hormone or have very similar symptoms to an underactive thyroid such as vitamin B12 deficiency.
Vitamin D is often low in people with hypothyroidism/Hashimoto’s disease and in those who spend a lot of time indoors, even in the summer and people do not often realise that this may be a cause of some of their symptoms so checking this vitamin can be a very good idea. People often do not want to bother their GP with this testing and it’s quick and convenient to test and monitor at home.
Thyroid UK, therefore, also suggests testing for nutritional status such as vitamin D, vitamin B12 and ferritin, which is not always available from clinicians on a regular basis.
Clinicians are extremely busy and have tight budgets. Therefore, if patients are willing and able to pay for private blood tests, this takes some of the workload away from clinicians.
Private testing laboratories inform patients if they are outside of any of the ranges Thyroid UK believes that if this is the case, the patient should make an appointment with their clinician to discuss their results and we firmly state this in our patient information.
We are aware of a number of cases where the patient has taken the results of their private tests to their clinician (GP and/or Endocrinologist) which has resulted in an amended treatment plan as it revealed issues not apparent from the NHS tests alone.
Thyroid UK checks that the testing laboratories we work with and their providers have the necessary accreditation and that the tests have been validated to ensure good quality of testing and management.
More information about the testing laboratories and their providers is available on request.
Date created: 28.09.23 (V1.0)
Review date: 28.09.24