Endocrine Disorders: Congenital Hypothyroidism (CH) Congenital Adrenal Hyperplasia (CAH)
Newborn Screening For Endocrine Disorders
Primary Congenital Hypothyroidism
Primary Congenital Hypothyroidism (CH) is a condition that affects the body's thyroid gland, a small organ in the lower neck. People with CH are unable to produce enough thyroid hormone, a chemical that is essential for healthy growth and development. If left untreated, CH can cause sluggishness, slow growth, and learning delays. However, if detected early and treatment is begun, individuals with CH often can lead healthy lives.
How common is primary congenital hypothyroidism?
In the United States, about one in every 3,000 to 4,000 babies is born with congenital hypothyroidism (CH). CH affects twice as many females as males. CH occurs in people of all ethnic groups around the world. It happens more often in babies from parts of the world in which there is not enough iodine in the food and water. It is also more common in babies of Hispanic, Asian, South Pacific, and Native American ancestry. It is less common in babies of African-American ancestry.
Most cases of CH (around 85 percent) are caused when the thyroid gland is missing, misplaced, or too small. About 80 to 85 percent of CH cases are sporadic. 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. 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. Anti-thyroid drugs can also put a developing baby at risk for CH.
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
Treatment for CH:
The most common treatment for 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 lacks. An endocrinologist can help determine the appropriate amount of L-thyroxine for your baby and write a prescription.
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.
Congenital Adrenal Hyperplasia
Congenital Adrenal Hyperplasia (CAH) is a collection of inherited conditions that affect the body's adrenal glands, which are the cone-shaped organs that sit on top of the kidneys. In a person with CAH, the adrenal glands are very large and are unable to produce certain chemicals, including cortisol, a chemical that helps protect the body during stress or illness and helps the body regulate the amount of sugar in the blood. Left untreated, the adrenal glands produce too much of chemicals called androgen, which produce male sex traits. Early detection and treatment can help children with CAH to have normal and healthy development.
How common is congenital adrenal hyperplasia?
In the United States, about one in every 15,000 babies is born with CAH. The condition may be more or less common in certain ethnic groups and geographic regions. For example, one out of 300 babies in the Yupik Eskimo population is born with CAH. The condition is less common in people of African-American and Asian descent. Non-classic CAH may occur in up to 1 in every 100 people. It appears to happen more often in people of Ashkenazi Jewish, Hispanic, Slavic and Italian background.
In 95% of CAH cases, the body does not make enough 21-OH enzymes. About 5% of CAH cases are not caused by 21-OH deficiency but other rare forms of CAH. Other causes of CAH may include Steroidogenic acute regulatory protein deficiency (STAR), 3-beta-hydroxysteroid dehydrogenase deficiency (3B-HSD), 17-alpha-hydroxylase deficiency, 11-beta-hydroxylase deficiency, Cytochrome P450 oxidoreductase deficiency
CAH is an autosomal recessive genetic condition. This means that a child must inherit two copies of the non-working gene for CAH, 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 CAH is rare, when both parents are carriers, they can have more than one child with the condition.
The signs of congenital adrenal hyperplasia (CAH) vary from person to person and by the form of CAH. There are three main forms of CAH:
- Salt-wasting classic CAH accounts for about 75% of classic CAH cases. This is the most severe form. Signs of salt-wasting CAH usually begin within the first few weeks of life. These signs include:
- Poor feeding
- Sleeping longer or more often
- Tiredness
- Vomiting
- Diarrhea
- Weight loss
- Irritability
- Rapid heart rate
- Male-like genitals in females
- Simple virilizing classic CAH accounts for about 25% of classic CAH cases. This form is less severe than salt-wasting CAH, but more severe than non-classic CAH. Signs of simple virilizing CAH begin before birth. These signs differ between males and females, which usually become apparent during childhood due to early puberty.
Early signs of simple virilizing CAH include:- Enlarged clitoris (it may look like a small penis)
- Labia that are fused together (they may resemble a scrotum)
- Small testicles
- Non-classic CAH is much less severe than classic forms of CAH. Signs of non-classic CAH can begin in childhood, adolescence, or adulthood. Both males and females with non-classic CAH may show signs of early puberty.
Treatment for CAH:
The main form of treatment for the classic forms of CAH is hydrocortisone pills. These pills help replace the cortisol that your baby's body cannot make naturally. An endocrinologist can help determine the appropriate dosage of hydrocortisone for your baby. Patients with the salt-wasting form of CAH require additional treatment with fludrocortisone, which replaces aldosterone. Babies who do not receive treatment for salt-wasting CAH are at risk for coma or death.
Your baby's doctor might prescribe medications or human growth hormone supplements to help regulate your child's growth. Children with CAH can experience delayed or rapid growth. X-rays can indicate if your child's bones are growing too quickly. Talk to your baby's doctor before starting this type of treatment.
Medications are also available to treat the early puberty that occurs during childhood in individuals with CAH. Your baby's doctor can write a prescription for these hormone medications.
Surgery
The genital changes associated with CAH can be reversed with surgery. Genital surgery is a very complex decision. What may be the right choice for one family might not be best for another family. It is important to talk to your baby's doctor about the risks and benefits of genital surgery in order to make an informed decision that is right for your child and family.