Congenital Adrenal Hyperplasia
Background
Congenital Adrenal Hyperplasia: CAH
Congenital Adrenal Hyperplasia is the name given to a group of enzyme disorders causing impaired production of cortisol (hydrocortisone) from the adrenal glands. By far the commonest type of CAH is 21 hydroxylase deficiency which occurs in roughly 1in 15,000 births. Production of cortisol and the salt-retaining steroid aldosterone is impaired but the androgen pathway (which produces the male hormone testosterone) is intact. The brain, sensing the low levels of cortisol, produces large amounts of adrenocorticotrophin hormone (ACTH) which stimulates the adrenal glands and causes enlargement (hyperplasia). Because of the enzyme block ACTH stimulation cannot normalise cortisol levels and instead results in over-production of androgen.