How is congenital adrenal hyperplasia diagnosed?
Congenital adrenal hyperplasia is diagnosed by a careful examination of the genitals and blood and urine tests that measure the hormones produced by the adrenal gland. A number of states in the United States perform a hormonal test (a heel prick blood test) for CAH and other inherited diseases within a few days of birth. In questionable cases, genetic testing
can provide a definitive diagnosis. For some forms of CAH, prenatal diagnosis is possible through chronic villus sampling in the first trimester and by measuring certain hormones in the amniotic fluid during the second trimester.
Children with CAH are treated urgently because the majority (75 percent) of these children are so-called "salt wasters." This means that the adrenal gland is not putting out enough of the mineral corticoid, which can cause the baby to rapidly lose salt. These babies require urgent steroid replacement or they could be at risk for going into shock.
If doctors suspect CAH on the initial newborn exam, the baby will be examined by pediatric specialists in urology and endocrinology right away. An accurate diagnosis can be made only after doctors take a detailed family history and perform a series of exams and tests that could take several days.
The examination includes a pelvic ultrasound. Here, doctors will look for female reproductive structures, such as a cervix, fallopian tubes and a uterus. The baby will also undergo a series of blood tests, including a test to determine the level of sex hormones in the blood as well as a chromosonal analysis (called karyotyping) to determine the genetic sex of the baby.
Some babies may need to undergo a genitogram, which allows doctors to visualize the outline of the reproductive structures. For this test, a contrast agent is injected into the reproductive tract and under X-ray imaging, doctors can visualize the outline of the reproductive system. In some cases, doctors will want to perform a gonadal biopsy.