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What is Congenital Adrenal Hyperplasia (CAH)?

Classical CAH

Classical CAH must be detected at birth to avoid an adrenal crisis, which can lead to death. In states and countries that screen for CAH at birth, the families will receive notification from their Department of Health or primary care physician that their child’s newborn screening test came back positive for CAH, and the infant requires immediate medical evaluation. With newborn screening, both male and female infants with this disease should be detected early enough to receive treatment before adrenal crisis occurs. Without newborn screening for CAH, the child is at risk for a life-threatening adrenal crisis, especially males, who show no outward physical manifestations of the disease.

Infant females generally come to medical attention at birth because the disorder causes affected females to exhibit recognizable genital anomalies resulting from high androgen levels while in the womb, and therefore receive prompt treatment for adrenal crisis and salt-wasting. The excess androgen exposure coming from the fetus’ adrenals during the period of gestation when the external genitalia are formed causes these external genital anomalies in females. The clitoris is usually enlarged, and may even look like a small penis, and the labial folds may be joined to resemble the scrotum. Sometimes, if the extent of ambiguity is great, the female baby may be misidentified as a male. These anomalies are only external. The female reproductive internal organs are not affected and are intact. The child has a uterus and ovaries. Some parents may choose reconstructive genital/urological surgery for their daughters. (See our section on Surgery for more in depth discussion of this issue.)

Infant males with CAH appear normal at birth. Newborn males show no external signs of the disorder and are sent home unrecognized. These babies often present with vomiting or life-threatening shock within the first few weeks of birth where there is no newborn screening.

Because the condition is life-threatening if not treated soon after birth, all 50 US states and many other countries require newborns to be screened for classical CAH. However, until all countries screen for CAH and other disorders detectable at birth, we will continue to advocate for comprehensive newborn screening including CAH.

When the adrenals cannot make sufficient aldosterone, too much salt and water are lost in the urine, leading to dehydration and salt deficiency. High levels of potassium can cause serious disturbances of heart rhythm and may lead to cardiac arrest. These babies become very ill soon after birth if not diagnosed and treated promptly. The remaining 25% of those with classical CAH who produce sufficient aldosterone are called “simple virilizers.” The nonclassical form of CAH is not life threatening, but can affect puberty and growth in children and can cause infertility in males and females as well as other symptoms affecting quality of life.