According to Tobias Else, M.D., of the Department of Internal Medicine at the University of Michigan in "Pathophysiology of Disease," congenital adrenal hyperplasia is a fairly common disorder. One out of every 5,000 to 15,000 children is born with this disease. Normally, the adrenal gland is responsible for making and secreting the hormones aldosterone, cortisol and androstenedione. The adrenal gland becomes hyperplastic, meaning the number of its cells increases, when it tries to make these hormones but is unable to do so.
17 Alpha-Hydroxylase Deficiency
Cortisol is a hormone that raises your glucose level. Androstenedione is a male hormone. The adrenal gland makes both of these hormones from cholesterol. But it needs 17 alpha-hydroxylase, which is an enzyme, to be able to make them. A deficiency of this enzyme means the gland does not have enough of the enzyme to make the hormones. This will send a signal to two areas of the brain. One part of the brain, called the anterior pituitary, will release a substance called ACTH. The ACTH will travel through the bloodstream to the adrenal gland and try to stimulate it to make cortisol. So much ACTH is sent, and the gland works so hard to try to make the hormones, that the adrenal gland becomes hyperplastic. A 17 alpha-hydroxylase deficiency is a hereditary disorder.
21 Beta-Hydroxylase Deficiency
The adrenal gland makes another hormone from cholesterol, which is called aldosterone. Aldosterone helps regulate blood volume and blood pressure. To make aldosterone, as well as cortisol, the adrenal gland needs an enzyme called 21 beta-hydroxylase. A deficiency of the 21 beta-hydroxylase enzyme means the adrenal gland does not have enough of this enzyme to make aldosterone and cortisol. As explained by Dr. Else in "Pathophysiology of Disease," this is the most common cause of congenital adrenal hyperplasia. For 90 percent of the children who have the disorder, it is because they have a deficiency of 21 beta-hydroxylase. When the adrenal gland cannot make these two hormones, this will send a signal to the two areas of the brain. Once again, the anterior pituitary of the brain will release the substance called ACTH. The ACTH will travel through the bloodstream to the adrenal gland and try to stimulate it to make aldosterone and cortisol. And once again, so much ACTH is sent and the gland works so hard, the adrenal gland becomes hyperplastic. A 21 beta-hydroxylase deficiency is also a hereditary disorder.
11 Beta-Hydroxylase Deficiency
The enzyme 11 beta-hydroxylase is another enzyme that is used by the adrenal gland to make aldosterone and cortisol. It is used in a different part of the process than 21 beta-hydroxylase. It is the second most common cause of congenital adrenal hyperplasia. Like the other causes, this deficiency is also hereditary. If the adrenal gland cannot make aldosterone and cortisol because it does not have enough of 11 beta-hydroxylase, this sends a signal to the brain. Once again, the anterior pituitary of the brain will release ACTH. The ACTH will go to the adrenal gland and try to stimulate it to make aldosterone and cortisol. And again, so much ACTH is sent and the gland works so hard, the adrenal gland becomes hyperplastic.
References
- "Handbook of Pathophysiology"; Elizabeth Corwin, MSN, Ph.D., FNP; 2000
- "Pathophysiology of Disease: An Introduction to Clinical Medicine"; Stephen McPhee, M.D., Gary Hammer, M.D., Ph.D.; 2010
