Hypothyroidism and Down’s Syndrome
Thyroid disease is more common in children with Down’s syndrome than in the general population.
By the time they are adolescents around 15% of those with Down’s syndrome will have an underactive thyroid and the frequency continues to rise throughout adulthood. This usually happens as a result of autoimmunity whereby the body is making antibodies that can attack the thyroid gland – a condition called Hashimoto’s hypothyroidism.
Less frequently the thyroid can become overactive when the body’s antibodies stimulate the thyroid gland– this condition is called Graves’ disease.
Common features of hypothyroidism are quite common in children and adults with Down’s syndrome and can be so subtle that thyroid disease can be difficult to diagnose.
- feeling the cold
- having a tendency to constipation
- having dry skin
- having sparse hair
- having a rather hoarse voice
For this reason the only sure way of recognising the need for treatment is by carrying out regular blood tests. It‘s important to do this because onset of hypothyroidism in a child with Down’s syndrome can lead to serious consequences including the plateauing of intellectual function and a slowing in growth.
The Down Syndrome Medical Interest Group (DSMIG) UK and Ireland therefore recommends that testing starts on a child’s first birthday and then continues every two years for life
Blood tests used to involve taking samples from the vein but in recent years it’s been possible to carry out limited thyroid testing using a few drops of fingerprick blood instead of a larger amount from the vein. Your family doctor may need to contact the local hospital laboratory to see if this is possible.
If there is a suspicion of a problem, the thyroid function tests that can be carried are
- Measuring the level of thyroid hormone thyroxine (often written as T4) – in the blood
- Detecting anti-thyroid antibodies
- Measuring the level of the thyroid stimulating hormone (TSH)
Measuring TSH levels alone may not be as helpful as in other circumstances as they can be difficult to interpret in children with Down’s syndrome. Quite a number of these children seem to produce raised TSH levels in early childhood for no obvious reason and these levels subsequently return to normal. Babies also may have transiently raised TSH levels after birth.
All three tests can be done on a single blood sample if the blood is taken from a vein. When fingerprick testing is used it is usually only possible to measure TSH.
At least 30% of adults with Down’s syndrome produce thyroid antibodies. However about half of them continue to produce enough thyroxine for the body’s needs and never need thyroid replacement therapy.
If replacement therapy is needed, this is much the same as for the general population whereby tablets, powders or liquid replacement thyroxine is prescribed. In children the regular blood tests along with a monitoring of weight/growth and symptoms are then required to ensure the dose of thyroxine is right for that individual child.
The dose may need to be adjusted from time to time and for children, of course, it is likely to need to increase as they grow.
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As the advice is general in nature rather than specific to individuals Dr Vanderpump cannot accept any liability for actions arising from its use nor can he be held responsible for the content of any pages referenced by an external link.