Congenital adrenal hyperplasia is the most common cause of ambiguous genitals in girls (genitals that are not clearly male or female at birth). Congenital adrenal hyperplasia refers to a group of inherited disorders of the adrenal glands (the adrenals are glands located on the top of each kidney that secrete several types of hormones). In some forms of this disorder, the glands are missing enzymes that help produce certain life-sustaining hormones, such as cortisol. Instead, the chemical building blocks that the glands use to make the cortisol are turned into male hormones, such as testosterone.
A Close Look at the Adrenal Glands
In infant girls, this build-up of testosterone causes them to develop male-appearing sexual characteristics (virilization). Infant girls with the most severe form look like boys with what appears to be a normal penis and scrotum. What appears to be the penis is actually the clitoris, which has been stimulated to grow by testosterone. What appears to be the scrotum is actually the labia, which have grown together. However, there are no testes (testicles) in the apparent scrotum. The girls also have darkened nipples and genitals.
In infant boys, the extra testosterone does not affect the appearance of their genitals. However, later in childhood, the penis and pubic hair start to develop at too young an age (early puberty).
Both boys and girls can develop life-threatening symptoms because their adrenal glands may not make enough of the normal adrenal hormones. Infants can have serious abnormalities of electrolytes (minerals such as sodium and potassium) in the blood and also become very dehydrated.
Infant girls and boys may need fluids given by vein (intravenously) and corticosteroids to treat dehydration and electrolyte abnormalities caused by the adrenal hormone deficiency.
Girls may need hormone supplements.
