when you should consider tests for thyroid disease
Last edited 12/2019 and last reviewed 08/2021
Investigating suspected thyroid dysfunction or thyroid enlargement
Indications for tests for thyroid dysfunction
Consider tests for thyroid dysfunction for adults, children and young people if there is a clinical suspicion of thyroid disease, but bear in mind that 1 symptom alone may not be indicative of thyroid disease.
Offer tests for thyroid dysfunction to adults, children and young people with:
- type 1 diabetes or other autoimmune diseases,
- or new-onset atrial fibrillation
Consider tests for thyroid dysfunction for adults, children and young people with depression or unexplained anxiety.
Consider tests for thyroid dysfunction 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.
Do not test for thyroid dysfunction during an acute illness unless you suspect the acute illness is due to thyroid dysfunction, because the acute illness may affect the test results.
Do not offer testing for thyroid dysfunction solely because an adult, child or young person has type 2 diabetes
Tests when thyroid dysfunction is suspected
Consider measuring thyroid-stimulating hormone (TSH) alone for adults when secondary thyroid dysfunction (pituitary disease) is not suspected. Then:
- if the TSH is above the reference range, measure free thyroxine (FT4) in the same sample
- if the TSH is below the reference range, measure FT4 and free tri-iodothyronine (FT3) in the same sample
Consider measuring both TSH and FT4 for:
- adults when secondary thyroid dysfunction (pituitary disease) is suspected
- children and young people
If the TSH is below the reference range, measure FT3 in the same sample.
Consider repeating the tests for thyroid dysfunction if symptoms worsen or new symptoms develop (but no sooner than 6 weeks from the most recent test).