Congenital Adrenal Hyperplasia - Facts and Information

Defining CAH

Congenital Adrenal Hyperplasia (CAH) involves an error with a person's steroid bio-synthesis. Persons with CAH due to 21 hydroxylase enzyme deficiency are unable to produce adequate amounts of cortisol and may also be be deficient in aldosterone as well. These two hormones are essential to the metabolism of glucose and the re-absorption of salt. Left untreated, CAH may suddenly lead to adrenal insufficiency accompanied with dehydration, shock, or perhaps even the death of the person. Once considered to be a rare inherited disorder with severe manifestations, mild CAH is common, affecting approximately one-percent of all women in America. Exact numbers of the people affected remain elusive because CAH frequently evades diagnosis.

The designation of, 'mild,' in association with a form of CAH is misleading. Even mild congenital adrenal hyperplasia may result in life-threatening pulmonary or sinus infections, shortened stature, orthostatic syncope, and severe acne. Women with mild CAH many time experience excessive hair growth, referred to as, 'hirsutism,' infertility, or irregular and skipped periods. Recognition of CAH and replacement therapy in a timely manner can help to reduce problems while enhancing the quality of life for persons who are affected by CAH.

Inheritance

Approximately ninety-percent of people with CAH experience 21 hyroxylase deficiency, the only form of CAH detected by newborn screening. This form of CAH is inherited in an autosomal recessive pattern, and as with other autosomal recessive disorders, the parents of a child with CAH are not affected. The parents are carriers of the condition, with each parent having one, 'normal,' gene and one, 'abnormal,' gene. The parents have a twenty-five percent chance of having a child with two copies of the abnormal gene that can result in CAH. Parents who carry the gene for CAH have a fifty-percent chance of having a child who is an unaffected carrier, and a twenty-five percent chance of having a child who is unaffected and does not carry the gene for CAH.

Physiology

A person's adrenal gland converts cholesterol into glucocorticoids, also known as cortisol, mineral corticoids (aldosterone), and sex hormones referred to as, 'androgens,' 'estrogens,' and, 'progestins,' in response to ACTH stimulation by their pituitary gland. Cortisol is the body's stress hormone; it controls carbohydrate and protein metabolism and is vital to a person's body's response to stresses like trauma, surgery, or infection. Aldosterone helps to keep a person's body fluid and electrolyte balance through promoting the re-absorption of sodium and excretion of potassium within their kidneys.

The male sex hormone, androgen, assists in controlling growth and sexual development. Before the twelfth week of gestation, fetal genital tissues are alike in both females and males. At approximately twelve-to-fourteen weeks, androgens from the testes in a male fetus result in male genital development. In infants with CAH, excess cortisol precursor is converted to excess androgen. In female infants, exposure to excess androgen while in the womb results in virilization. Infants who have CAH can rapidly develop adrenal insufficiency, metabolic acidosis, hypoglycemia, dehydration and shock.

Symptoms

Female infants who are born with 21 hyroxylase deficient CAH commonly have some level of, 'virilization,' or ambiguous genitalia, caused by exposure to excessive androgen levels while they are in the womb. Male infants might have an enlarged scrotum and penis with increased pigmentation. An infant with CAH can experience symptoms of salt wasting CAH that includes frequent urination. In some cases, the infant may feed poorly, rapidly leading to vomiting, dehydration, electrolyte changes and cardiac arrhythmia. Infants with CAH who are not diagnosed and treated at an early stage are very susceptible to sudden death within the first few weeks of their lives. Older children with CAH might experience rapid growth and premature skeletal maturation.

Newborn Screening

Congenital adrenal hyperplasia may be diagnosed through a demonstration of excess cortisol precursors in the person's blood, particularly after a test injection of a drug known as, 'ACTH.' A diagnosis of CAH in an unborn child may be made through an amniocentesis. Screening for CAH due to 21 hydroxylase deficiency may be done through a fluorimetric assay to measure the 17 hydroxy progesterone level. False positive and false negative results are possible with the screening. If a specimen is collected before the infant is twenty-four hours old, or premature or ill, it can affect the screening; physiological stress may cause an elevation of the 17 hydroxy progesterone level. Treatment with either Dexamethasone or hydrocortisone can result in false negative screening results.

Infants who have been screened using this method and have a presumptive positive result need prompt follow-up. Upon receiving the results, a medical professional should check the infant's status and refer the infant to a pediatric endocrinologist. Measurement of the infant's serum 17 hydroxy progesterone level and serum electrolytes should also be pursued. Additional testing is required because of the seriousness of CAH.

Treatment

Treatment of congenital adrenal hyperplasia includes monitored hormone replacement therapy and a lifetime of daily medication. Missing cortisol is replaced with oral hydrocortisone in children, and with Dexamethasone or prednisone for older children. Hydrocortisone is commonly administered at regular intervals, three times per day. For people who experience salt wasting CAH, in addition to hydrocortisone - fludrocortisone is also prescribed in order to correct aldosterone deficiency. Small children and infants with salt wasting CAH might also need salt tablets as a dietary supplement. Regulating the dosage of medications is vital because an improper dosage may have the result of delaying growth, or premature bone epiphyseal closure. Female infants with ambiguous genitalia might require re-constructive surgery.

Information for Parents

For parents, it is important to understand that treatment of CAH is lifelong and that compliance with the medication regimen is essential. Frequent blood monitoring is imperative to your child's health, development and growth. Children with CAH are usually healthy, but any form of illness such as vomiting, fever, or an injury, is something that the child's doctor need to be promptly notified about because their cortisol dosage may need to be increased. Parents of a child with CAH should always keep injectable hydrocortisone on hand at all times. If the child experiences repeated vomiting, or cannot hold down fluids, a health care professional should be contacted immediately.

Parents also need to understand that the treatment their child with CAH is receiving is not curative. Long-term management, monitoring and compliance with the recommended treatment the child's doctor has provided are essential to the well-being of their child. It is important to follow through with the recommendations of health care workers in pediatrics and endocrinology. Infants and children with CAH should have regular follow-up appointments with a pediatric endocrinologist to monitor their medications.