What is Congenital Adrenal Hyperplasia Due to 21-Hydroxylase Deficiency?

Congenital Adrenal Hyperplasia (CAH) includes a group of disorders, each characterized by a deficiency of one of the enzymes needed to make the hormone cortisol.

Cortisol is a steroid hormone necessary to the following body functions:

There are several different forms of CAH, each related to one of the enzymes necessary to transform cholesterol to cortisol (hydrocortisone). These enzymes are: StAR / 20,22-hydroxylase, 3-hydroxysteroid-dehydrogenase / 17-hydroxylase / 21-hydroxylase and 11-hydroxylase.

When one of these enzymes is deficient, this leads to a hyperfunction and increased size (hyperplasia) of the adrenals, hence the name Congenital Adrenal Hyperplasia. Among the various forms of CAH, the 21-hydroxylase deficiency is by far the most frequent, representing more than 90% of all cases.

This is the only form to be discussed here. First, normal adrenal function will be presented, followed by a discussion of adrenal function in 21-hydroxylase deficiency and its treatment.

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