This fact sheet is designed to answer five important questions about congenital hypothyroidism:
- What is the thyroid gland and what does it do?
- What is congenital hypothyroidism?
- What did I/we do to have this happen to my/our child?
- How does this affect my child?
- How is it best treated?
The thyroid gland is an organ located at the base of the neck, just above the top of the breastbone. It is a soft, fleshy, flat piece of tissue shaped like a butterfly, located in front of the trachea (windpipe). The thyroid gland is formed during the first few weeks of a fetus' development and begins to produce its important hormone at the end of the third month of pregnancy.
The hormone produced by the thyroid gland is called THYROXINE or T4 (or simply, thyroid hormone). Thyroxine circulates through the bloodstream to all the tissues of the body and is very important for many body functions, particularly those related to the body's metabolism. During infancy, its most vital role is to ensure that the growth and development of the baby's brain occur normally. It is also very important for normal growth of the body and skeleton as a whole, keeps the body temperature normal, and helps ensure that muscle and fat are distributed normally in the body.
Under normal circumstances, the thyroid gland is regulated by the body's "master gland" - the pituitary gland, which is a small pea-sized organ located at the base of the brain. The pituitary gland registers whether the body is receiving enough thyroid hormone (thyroxine) and sends out a signal (a hormone called Thyroid Stimulating Hormone, or TSH), when the body's levels of thyroid hormone are too low. If the levels of thyroid hormone are low, then the levels of TSH will increase to try to "drive" the thyroid gland to make more thyroxine. This is the basis of the blood testing performed to evaluate the treatment of a child with congenital hypothyroidism.
The word "congenital" means that the child is born with the condition. It has nothing to do with the genitals, and does not necessarily mean that the condition is inherited or genetic in nature. The term "hypothyroidism" means underactive thyroid gland (HYPO is Greek for "Under"). There are a variety of different causes of underactivity of the thyroid gland in a newborn child. First, the thyroid gland simply may not have developed at all. This condition is called "athyreosis", meaning "absent thyroid gland". Second, it may have developed abnormally, and may be smaller than normal (hypoplastic) or misplaced to an abnormal location, such as at the back of the tongue (ectopic). In these cases the thyroid gland may produce thyroid hormone initially, but will usually "run out of steam" as the child grows . The third form of congenital hypothyroidism results from a different type of problem. In this case the thyroid gland develops normally. However, one of the many enzymes within the gland required to produce the hormone is missing or malfunctioning (this is like having a new car that is missing a spark plug - the engine won't run without it).
About 1 in every 5,000 babies is born with congenital hypothyroidism. This means that each year in Indiana, there are about 20 - 30 babies born with this condition. It is very important that you, as parents, understand that there is nothing that you did or did not do, either before or during pregnancy, that either caused this to happen or could have prevented this condition from developing.
Congenital Hypothyroidism is detected in the newborn infant by finding a high level of TSH (the hormone produced by the pituitary gland that controls the thyroid gland) and/or a low level of thyroxine (the hormone produced by the thyroid gland) on the blood spot collected for the Newborn Screen. Section 1 above, describes the interaction between the thyroid gland and the pituitary gland.
As there are at least 3 different causes of congenital hypothyroidism, it is recommended that your child undergo a diagnostic thyroid scan, to try to determine the exact type of hypothyroidism that your child has. This is important because about 10 - 20% of cases of Congenital Hypothyroidism may be caused by an inheritable problem, and the thyroid scan may help us to determine whether or not your child's hypothyroidism is likely to be inheritable.
It is very important that you, as parents, understand that there is nothing that you did or did not do, either before or during pregnancy, that either caused this to happen, or could have prevented this condition from developing. Although you are understandably sad about the fact that your baby requires medication, it is important to remember that many children are born with some kind of congenital disorder, and that you are very much in control of this condition and can prevent it from harming your child.
If your child has the less common type of hypothyroidism, due to defective enzyme function in the thyroid gland (about 10 % of cases), then it is possible that you, the baby's parents, carry a gene that is malfunctioning and that the combination of 2 malfunctioning genes in the same child is the cause of the disorder. To determine if this is the case requires more specialized testing. You will need to discuss this with your doctor.
Congenital hypothyroidism cannot be prevented, but it certainly can be treated very easily and very effectively. Thyroid hormone is critical for the development of the infant brain. This is its most important role in the newborn. If an infant does not have any thyroid hormone, he or she is at risk of suffering severe problems related to brain growth and development. For this reason there is a high incidence of mental retardation in UNTREATED children with congenital hypothyroidism. Fortunately, early diagnosis and treatment of congenital hypothyroidism can prevent this serious problem. It is for this reason that Newborn Screening for Congenital Hypothyroidism is THE LAW in all 50 states. Untreated hypothyroidism, or hypothyroidism that is treated too late, or with inadequate doses of thyroid hormone, places at risk the development and intelligence of the affected child. However, it is important for you to you know that the overwhelming majority of children who receive proper treatment of this condition have NO MENTAL DEFICIENCY. Children with Congenital Hypothyroidism who receive appropriate thyroid medication live entirely normal lives, grow and develop normally, and can do as much mischief as a child whose thyroid hormone is produced from his or her own thyroid gland!
The most critical factor in ensuring that a child with congenital hypothyroidism does not suffer any damage from this condition, is to provide treatment AS SOON AS POSSIBLE after birth. The second very important aim is to ensure that the child is treated with the correct dose of thyroid hormone during infancy and for the first 2 - 3 years of life - the time during which the majority of brain growth occurs. The American Academy of Pediatrics has published guidelines for the correct treatment of this condition during infancy. In general, they recommend that full term babies receive 37.5 micrograms (abbreviated as ug or mcg) per day of synthetic thyroid hormone, levothyroxine (Levoxyl, Synthroid, Levothroid etc). The dose of levothyroxine will probably need to be increased steadily as your child grows, to keep up with the increasing body needs.
Unfortunately, levothyroxine comes only in tablet form. The different tablet strengths have different colors. You should be aware of the exact dose of medication your baby is taking each day. Try the following methods to give the medication to your baby:
- try to give the medication at about the same time each day. If you have trouble remembering things like medications, try placing a calendar on the door of the refrigerator or bathroom cabinet (wherever you keep the tablets) and checking it off daily after you have given the medication.
- break the tablet(s) along the line as necessary, depending on your child's dose of medication.
- crush the tablet(s) between 2 spoons, then mix with a small amount of breast milk, water, or formula in a the spoon or in a medicine cup. Mix with liquid at room temperature only. Do NOT mix with soy formula. This blocks the stomach from absorbing the medication, and can result in persistently low thyroid hormone levels.
- draw up the medication into a syringe or dropper and slowly squirt this into the side of your baby's mouth, next to the cheek. Do not put the medication into the baby's bottle, since some medicine will be lost if your baby does not finish the bottle.
- for older infants, the tablets can be mixed with a small amount of a soft food such as apple sauce, baby fruit, cereal, jelly etc. This can be given by teaspoon into the baby's mouth. Be sure to mix the medication with something that your baby likes, so that he or she will swallow the medicine. Do not mix it into the whole bowl of food, since some medicine will be lost if your child does not finish the food.
- some babies will actually just chew up the tablet like candy. If your baby will do this -- LUCKY YOU -- it makes it even easier to give the medicine. Try it some time.
- If your baby has a tendency to spit up, give the medication at least 30 minutes before he or she is fed. If your baby spits up the medication, give the same dose again.
- If you have trouble remembering things like doses of medication, either write the dose in your diary, or bring the bottle of tablets with you to your visits with your pediatrician or pediatric endocrinologist.
To ensure that blood levels of the hormones are correct it is recommended that the levels be checked:
- every month for the first 6 months of life
- every 2 months from 6 months to 12 months of age
- every 3-4 months from 12 to 24 months of age
- every 4-6 months from 2-5 years of age
- every 6 months thereafter
These recommendations are made to ensure that your child receives the correct dose of hormone - neither too little, nor too much - since either an excess or a deficiency can cause problems.
As you now understand , the correct dosing of hormone is critical, therefore it is vital that your child receive the dose of hormone prescribed on a regular daily basis, without missing doses. It is also very important that the hormone levels be checked regularly, according to the schedule described above, to ensure that the hormone levels are within the correct range.
Other things that will help you to know whether your child is receiving an appropriate dose of thyroid hormone are, first, your child's growth. A child with congenital hypothyroidism who is receiving appropriate treatment should show steady growth along his or her appropriate percentile channel (this is judged on the basis of genetic background - heights and weights of parents)--ask for a copy of your child's growth chart. Second, there are symptoms of inadequate thyroid hormone levels to watch for: constipation, lack of energy, dry skin and hair, poor school performance--all of these would suggest the need to recheck the thyroid hormone levels in the blood and perhaps adjust the dosage if needed.
For More Information
If you have any questions regarding your baby's hypothyroidism or its treatment, please call your pediatrician.
Alternatively, you are invited to call the Indiana Congenital Hypothyroidism Follow-Up Program and speak with the Riley Hospital for Children Endocrinology at Indiana University Health nurse or doctor caring for your child.
Our telephone number is: 317.944.3889.