EARLY SIGNS
Most babies with primary congenital hypothyroidism (CH) show signs at three to four weeks after birth. Early signs of CH include:
- Yellow skin or eyes (known as jaundice)
- Sleeping longer or more often
- Constipation
- Weak muscle tone (called hypotonia)
- Swelling around the eyes
- Swollen tongue
- Cool, pale skin
- Large belly with a navel that sticks out
- A hoarse-sounding cry
- Delayed growth and weight gain
CAUSES
In our bodies, glands make hormones. Hormones send messages to cells throughout the body. These messages control all sorts of functions, such as breaking down food or mental and physical development.
Primary congenital hypothyroidism (CH) occurs when the thyroid gland is not working properly. The thyroid gland is a gland in the neck that makes a hormone called thyroid hormone. Thyroid hormone helps control growth, brain development, and how we break down food for energy.
About 80 to 85 percent of CH cases are sporadic. This means that:
- The condition was not passed on from parent to child.
- An affected individual cannot pass this condition on to his or her children.
- Brothers and sisters are usually not at risk of having CH.
In these cases, the thyroid gland does not develop correctly. It may be completely missing, located in the wrong place, or too small to make enough thyroid hormone.
About 15 percent of CH cases are considered to have a genetic cause.
In this case, CH is usually an autosomal recessive genetic condition. This means that a child must inherit two copies of the non-working gene for CH, one from each parent, in order to have the condition. The parents of a child with an autosomal recessive condition each carry one copy of the non-working gene, but they typically do not show signs and symptoms of the condition. While having a child with CH is rare, when both parents are carriers, they can have more than one child with the condition.
A geneticist or genetic counselor can help you determine if your child has an autosomal recessive genetic case of CH. All the ways genetic-based CH is inherited are not yet well understood. CH may also be inherited by autosomal dominant or X-linked recessive patterns.
In very rare cases, CH is caused by an iodine deficiency in the mother during pregnancy. Iodine is a natural substance that the thyroid gland needs for healthy development. If a pregnant woman does not consume enough iodine, her baby may be at risk for CH. Anti-thyroid drugs can also put a developing baby at risk for CH.
TREATMENT
Medications
The most common treatment for primary congenital hypothyroidism (CH) is thyroid hormone replacement therapy. Your baby may need to take L-thyroxine pills, a synthetic thyroid hormone, to replace the natural thyroid hormone that his or her body does not make enough of. An endocrinologist can help determine the appropriate amount of L-thyroxine for your baby and write a prescription (see Accessing Care).
Dietary Restrictions
If your baby is taking thyroid hormone pills, you may need to restrict the amount of soy and iron in his or her diet. Soy and iron affect how the body absorbs thyroid hormones from the pills. Tell your baby’s doctor if your baby eats soy-based formula or takes iron supplements.
EXPECTED OUTCOMES
If treatment starts soon after birth, children with primary congenital hypothyroidism (CH) can have healthy growth and development. This is why newborn screening for CH is so important.
Treatment will need to continue throughout your child’s life. This may require regular check-ups to monitor thyroid hormone levels, growth, and development.
Some children may still have trouble in school or delayed growth, even with treatment. Children who struggle in school may need extra help or an early intervention program to prepare them for school.
Delayed treatment can put children at risk for intellectual disabilities, learning disabilities, developmental delays, and delayed growth.