NICE summary
The recommendations in this Best Practice topic are based on authoritative international guidelines, supplemented by recent practice-changing evidence and expert opinion. For your added benefit, we summarise below the key recommendations from relevant NICE guidelines.
Key NICE recommendations on diagnosis
This summary covers thyroid disease in non-pregnant people.
Consider tests for thyroid dysfunction if there is clinical suspicion of thyroid disease, but bear in mind that 1 symptom alone may not be indicative of thyroid disease.
When thyroid dysfunction is suspected:
In adults (aged 16 and over), consider measuring:
Thyroid-stimulating hormone (TSH) alone when secondary thyroid dysfunction (pituitary disease) is not suspected
Both TSH and free thyroxine (FT4) when secondary thyroid dysfunction is suspected
In children and young people, consider measuring both TSH and FT4.
If TSH is:
Above the reference range, then measure FT4 (if not already done) in the same sample
Below the reference range, then measure FT4 (if not already done) and free tri-iodothyronine (FT3) in the same sample.
Offer tests for thyroid dysfunction to people with type 1 diabetes or other autoimmune diseases, or new-onset atrial fibrillation.
Do not offer thyroid dysfunction testing solely because a person has type 2 diabetes.
Consider tests for thyroid dysfunction for people with depression or unexplained anxiety, and for children and young people with abnormal growth or unexplained change in behaviour or school performance.
Be aware that in menopausal women symptoms of thyroid dysfunction may be mistaken for menopause.
Ask people with suspected thyroid dysfunction about their biotin intake because a high consumption of biotin from dietary supplements may lead to falsely high or low test results.
Do not test for thyroid dysfunction during an acute illness unless you suspect the illness is due to thyroid dysfunction, because the acute illness may affect the test results. Test once the illness has resolved.
Consider repeating tests for thyroid dysfunction if symptoms worsen or new symptoms develop. Do not do this sooner than 6 weeks from the most recent test.
If primary hypothyroidism is confirmed:
In children and young people, measure thyroid peroxidase antibodies (TPOAbs), with possible repeat TPOAbs testing at the time of transition to adult services
In adults, consider measuring TPOAbs, but do not repeat TPOAbs testing.
If subclinical hypothyroidism is confirmed, consider measuring TPOAbs in adults (but do not repeat TPOAbs testing).
For information on testing for coeliac disease in people with a diagnosis of autoimmune thyroid disease, see the NICE guideline Coeliac disease: recognition, assessment and management (NG20).
Links to NICE guidance
Thyroid disease: assessment and management (NG145) October 2023. https://www.nice.org.uk/guidance/ng145
Key NICE recommendations on management
Management and monitoring of primary hypothyroidism
Offer levothyroxine as first-line treatment for people with primary hypothyroidism.
Do not routinely offer liothyronine (either alone or in combination with levothyroxine) and do not offer natural thyroid extract for primary hypothyroidism.
Aim to maintain TSH levels within the reference range when treating with levothyroxine.
If symptoms persist, consider adjusting the dose to achieve optimal wellbeing, but avoid using doses that cause TSH suppression or thyrotoxicosis.
Consider when adjusting the dose that the TSH level can take up to 6 months to return to within range if it was very high before treatment or if there was a prolonged period of untreated hypothyroidism.
In adults taking levothyroxine for primary hypothyroidism, consider measuring:
TSH every 3 months until the level has stabilised (2 similar levels within range 3 months apart), and then once a year
FT4 (as well as TSH) if symptoms continue after starting levothyroxine.
In children and young people taking levothyroxine, consider measuring TSH and FT4:
In those aged 2 years and over every 6 to 12 weeks until the TSH level has stabilised (2 similar levels within range 3 months apart), then every 4 to 6 months until after puberty, then once a year
In children aged between 28 days and 2 years every 4 to 8 weeks until the TSH level has stabilised (2 similar levels within range 2 months apart), then every 2 to 3 months during the first year of life, and every 3 to 4 months during the second year of life.
Management and monitoring of subclinical hypothyroidism
When discussing whether or not to start treatment for subclinical hypothyroidism, consider features suggesting underlying thyroid disease, such as:
Symptoms of hypothyroidism
Previous radioactive iodine treatment or thyroid surgery
Thyroid dysgenesis
Raised levels of thyroid autoantibodies.
In adults with subclinical hypothyroidism, consider:
Levothyroxine if TSH is ≥10 mlU/litre on 2 separate occasions 3 months apart (as this may improve symptoms and may have long-term benefits including on cardiovascular outcomes)
A 6-month trial of levothyroxine for adults under 65 years with a TSH <10 mlU/litre on 2 separate occasions 3 months apart and symptoms of hypothyroidism
If symptoms do not improve after starting levothyroxine, re-measure TSH and if it remains raised, adjust the dose. If symptoms persist when TSH is within range, consider stopping levothyroxine (as the symptoms are likely to be due to causes other than hypothyroidism) and monitor appropriately (see below).
In children and young people with subclinical hypothyroidism, consider levothyroxine for:
Those aged 2 years and over with a TSH level:
≥20 mlU/litre, or
Between 10 and 20 mlU/litre on 2 separate occasions 3 months apart, or
Between 5 and 10 mlU/litre on 2 separate occasions 3 months apart and thyroid dysgenesis or signs or symptoms of thyroid dysfunction
Children aged between 28 days and 2 years with a TSH level ≥10 mlU/litre.
Follow up and monitor people with subclinical hypothyroidism who are taking levothyroxine as for people with primary hypothyroidism (see above section).
In adults with untreated subclinical hypothyroidism or adults who have stopped levothyroxine treatment for subclinical hypothyroidism, consider measuring TSH and FT4:
Once a year if they have features suggesting underlying thyroid disease, or
Once every 2 to 3 years if they have no features suggesting underlying thyroid disease.
In children and young people with untreated subclinical hypothyroidism, consider:
Measuring TSH and FT4:
Every 3 to 6 months in those aged 2 years and over with a TSH <10 mlU/litre and features suggesting underlying thyroid disease, or
Every 6 to 12 months in those aged 2 years and over with a TSH <10 mIU/litre and no features suggesting underlying thyroid disease, or
Every 1 to 3 months in children aged between 28 days and 2 years
Stopping TSH and FT4 measurement if TSH has stabilised (2 similar levels within range 3 to 6 months apart) and there are no features suggesting underlying thyroid disease.
© NICE (2023) All rights reserved. Subject to Notice of rights NICE guidance is prepared for the National Health Service in England https://www.nice.org.uk/terms-and-conditions#notice-of-rights. All NICE guidance is subject to regular review and may be updated or withdrawn. NICE accepts no responsibility for the use of its content in this product/publication.
Links to NICE guidance
Thyroid disease: assessment and management (NG145) October 2023. https://www.nice.org.uk/guidance/ng145
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