Thyroid
Thyroid issues are common in children and adults who have Down’s syndrome. The thyroid gland is in the front of your neck just below the Adam’s apple. The gland produces a number of different hormones, the main ones being thyroxine (T4) and triiodothyronine (T3). These hormones help the cells in the body to work properly. They help regulate the body’s energy levels and play a part in physical and mental development.
Thyroid blood tests and what they mean
Thyroid issues are very common for people who have Down’s syndrome so regular thyroid blood tests are recommended. Babies should have a routine heel prick blood spot test in the first six weeks of life followed by a screening blood test between four and six months of age.
From the age of 1 year, a blood test should be done every year (or more often if clinically indicated) for the rest of life.
Anyone who has Down’s syndrome (age 14 years and over) is entitled to a free learning disability annual health check with their GP – thyroid should be tested as part of the annual health check.
The thyroid gland produces thyroid hormone, in the form of T3 and T4.
When it is overactive, the thyroid gland produces too much thyroid hormone. This causes symptoms such as sweating, feeling hot, weight loss, fast heart rate and others.
When it is underactive the thyroid gland produces too little thyroid hormone. This causes symptoms such as dry skin, feeling cold, weight gain, lethargy and others.
The thyroid gland is driven by the pituitary gland. The pituitary gland produces a hormone called Thyroid Stimulating Hormone (TSH) which causes the thyroid gland to produce thyroid hormone.
Problems with under or overactive thyroid can be caused by issues anywhere along this pathway.
Often, when thyroid function is checked, both TSH and T4 are measured.
If both are normal, this is fine.
If TSH is high but T4 is normal, it often means a problem with the thyroid gland. The pituitary gland is having to produce more TSH than normal to drive the thyroid gland. Medication isn’t usually needed, as the T4 level is still normal, but this needs to be watched, as the T4 level might start to drop as the thyroid gland becomes more underactive.
If the TSH is high but the T4 is low, the thyroid gland is struggling to produce enough T4 even when the pituitary gland is doing its best to drive it. The thyroid gland is now underactive and medication must be taken to replace the thyroid hormone which is not being produced.
If the TSH is low and the T4 is low, the pituitary gland is not driving the thyroid properly, so the pituitary gland is causing a problem and this must be investigated and treated.
If the TSH is low but the T4 is normal, the thyroid gland is producing lots of thyroid hormone and is not needing to be driven by the pituitary gland. This needs to be observed, as the thyroid gland may start to produce too much thyroid hormone.
If the TSH is low but the T4 is high, the thyroid gland is now overactive and producing too much thyroid hormone, despite the pituitary gland trying to slow it down. Medication is needed (and sometimes other treatments such as radioiodine or surgery) to switch off the thyroid gland.
If the TSH is high and the T4 is high, the thyroid is overproducing thyroid hormone because the pituitary gland is driving it too hard. Treatment is needed to switch off the pituitary gland.
In people who have Down’s syndrome, most thyroid issues are due to the thyroid gland and not the pituitary gland.
Other tests may include T3 (the other, less important thyroid hormone) and thyroid antibodies (these are important in cases where the body attacks itself – autoimmune conditions).
This is all made more complicated by the fact that different laboratories use different machines, with different normal ranges for TSH, T3 and T4.
The TSH normal level varies depending on the laboratory, but the upper limit is often around 4-5.5.
The T4 normal level also varies, but the upper limit is often around 11-12.
Normal levels for people who have Down’s syndrome are the same as for those without.
T3 is less often measured as it is usually the last of the thyroid tests to become abnormal – i.e. if TSH and T4 are normal, T3 is likely to be, too.
The DSMIG produces guidance for health professionals on which tests to do, how often and what to do about the results. These can be found at the link at the end of this page.
Further Info & Advice
If you have any questions about health issues, you can call DSA’s Helpline (Tel: 0333 1212 300) or email using info@downs-syndrome.org.uk. If an information officer is unable to answer your question, they can make a referral to the medical adviser at the UK & Ireland Down Syndrome Medical Interest Group (DSMIG).
Please note DSMIG can provide general advice about health issues but they are not able to comment on individual test results. DSMIG are happy to take enquiries from health professionals but they will not take direct from enquiries from families or supporters.
Resources and useful organisations
Down’s Syndrome Association
Other
The DSMIG (UK & Ireland) Guidelines on Thyroid Disorder in children and young people with Down Syndrome
Guidelines on thyroid disorder in children and young people with Down syndrome: surveillance and when to initiate treatment. Published April 2020.
NHS.UK page on underactive thyroid (hypothyroidism)
An overview of the condition including symptoms, causes, diagnosis, treatement and complications.
British Thyroid Foundation
Advice on the treatment and care of thryoid disorders.