What does a thyroid scan involve?

The simple heel prick test is a vital health check for new babies


My baby’s heel prick test came back positive for congenital hypothyroidism; he now needs a thyroid scan. What will this involve and, if he does have the condition, what will the treatment be?

Thank you for asking this question – many parents don’t know what the heel prick blood test is and why it’s done, so this gives me a chance to explain it. The test (sometimes called the Guthrie test after Robert Guthrie who created it in 1962) involves a small sample of blood being taken from your baby by pricking their heel; we suspect babies hardly feel it at all. It’s usually done around the fifth day of your baby’s life and is a critical test as it screens for nine serious conditions.

We look for six inherited metabolic conditions, as well as sickle cell disease, cystic fibrosis, and congenital (meaning from birth) hypothyroidism (CHT). If you have this condition, the thyroid gland doesn’t work well – or not at all; in rare cases, babies are born without a thyroid. The thyroid gland produces a hormone, thyroxine, which is critical to growth, the development of the brain and many body functions. According to current data about 1 in 3,000 babies in the UK may have abnormal thyroid function at birth.

If CHT is detected, a scan is often done to check the appearance of the thyroid, which is in the middle of the neck in front of the windpipe. Other blood tests may also be done to find the exact levels at which the thyroid is working.

But now for the good news. In most cases, when detected early, CHT is very treatable – a replacement for thyroxine can be given every day, in a pill or liquid. This is a lifelong treatment, but as the consequences of not taking it can be huge it seems a small price to pay. So good luck, be brave and try not to worry. And be comforted: your question shows how important the heel prick test is.

Dr Peter Ilves


Dr Peter Ilves is a GP and mental health expert with a keen interest in helping people to take a more active role in their own care. Got a question for the panel? Email experts@gurgle.com.

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