Hypothyroidism refers to an underactive thyroid gland. Congenital hypothyroidism occurs when a baby is born without the ability to make normal amounts of thyroid hormone.
It occurs in about 1 in 3,000 to 4,000 newborn babies. Thyroid hormone is important for your baby’s physical (height and weight) and mental (brain) development therefore, untreated congenital hypothyroidism can lead to intellectual disability, growth failure and slow metabolism.
Congenital hypothyroidism is one of the preventable causes of mental retardation. Hence, with early diagnosis and treatment, your baby can lead a normal healthy life.
What causes Congenital hypothyroidism?
Congenital hypothyroidism most often occurs when the thyroid gland does not develop properly. The gland could be completely (aplasia) or partially missing or small in size (hypoplasia) or it has not come to its normal position in the neck (ectopic).
Sometimes the gland is formed properly but does not produce hormone in the right way (dyshormonogenesis). In a small number of cases, medications taken during pregnancy, mainly those for treating an overactive thyroid, can lead to congenital hypothyroidism, which is temporary in most cases.
Congenital hypothyroidism is usually not inherited through families. This means that if one baby is affected, it is unlikely that other babies may have the same condition in the future.
What are the signs and symptoms of congenital hypothyroidism?
The symptoms of congenital hypothyroidism in the first week after birth are not usually obvious.
However, sometimes, when hypothyroidism is severe, there may be poor feeding, excessive sleeping, weak cry, constipation, and prolonged jaundice (yellow skin) after birth.
When examining these babies doctors may find a puffy face, poor muscle strength, and a large tongue with a distended abdomen and larger than normal fontanelles (soft spots) on the head.
How is congenital hypothyroidism diagnosed?
A very simple test can diagnose congenital hypothyroidism. 3 drops of blood is collected from baby’s heel on 3rd or 4th day of birth and sent for thyroid hormone assessment. This is called newborn screening.
If the reports are abnormal a repeat blood sample from a vein is taken to confirm the diagnosis of congenital hypothyroidism.
If report is positive for congenital hypothyroidism your Paediatric endocrinologist would do a thyroid scan (to check the function), ultrasound of the thyroid gland (for position and size) and an X-ray of both knees of your baby before starting treatment.
How is congenital hypothyroidism treated?
Congenital hypothyroidism is treated by giving thyroid hormone medication in a pill form called levothyroxine.
Levothyroxine should be crushed and given on empty stomach once daily, mixed with a small amount of water or breast milk.
If given with food, it can interfere with the absorption of the levothyroxine from your baby’s gastrointestinal tract.
How Often Are Blood Levels Checked?
Monitoring of TSH and free T4 is essential. Generally, blood tests are checked every 2-4 weeks initially till 6 months and then every 2 to 3 months thereafter.
Is Lifelong Treatment Necessary?
For some babies, thyroid hormone replacement therapy will be needed for their entire life. They lead a normal healthy life if the medicine is given regularly with growth monitoring.
For the other babies, where thyroid hormone deficiency is transient, with treatment is required for 2-3 years of age.