Congenital Adrenal Hyperplasia
Written by Professor Garry L Warne , Illustrations by Jocelyn Bell
Updated in 2021 by the RCH Endocrinology, Gynaecology and Urology teams.
CAH is a fairly uncommon diagnosis, but one which is well understood and for which good treatment is readily available. People with CAH enjoy excellent health and
the condition does not impact on life expectancy. They can do anything they want to, including building careers, forming relationships and having children. To maintain this state of good health, people with CAH do need to take medications, but this becomes accepted as part of life. CAH is a nuisance, but not a handicap. CAH peer support group for people with CAH, their parents and their friends exist and can provide support and assistance, your doctor or clinical coordinator can put you in touch with them or you may find them on the internet.
There are peer support groups that cover a spectrum of variations in sex characteristics that can also give you support, these include groups such as the Intersex Peer Support Australia and the Congenital Adrenal Hyperplasia Peer Support Group Australia CAH SGA.
The nature of CAH
CAH is congenital meaning it is present at birth. CAH involves the hormones of the adrenal glands. The word ‘hyperplasia’ means ‘overgrown’. In CAH, the child is born with overgrown adrenal glands.
What are hormones?
Hormones are the chemical messengers in the body. They are produced in one place by an endocrine or hormone-producing gland, and act somewhere else in the body. Female type sex hormone, for example, is made in the ovaries and acts elsewhere in the body to cause breast enlargement, broadening of the hips, and periods. There are many different types of hormones and many endocrine glands, each of which makes its own special hormones. In trying to understand CAH, the most important glands to consider are the adrenal glands and the pituitary gland.
What are the adrenal glands?
The adrenal glands are a pair of fleshy triangular-shaped organs, each about the size of a walnut, which lie above the kidneys, on the back wall of the abdomen.
Although fairly small, the adrenal glands make some of the most important hormones, ones that we cannot do without. In children with CAH, some of the complex chemical ‘machinery’ needed to make the essential hormones do not work properly and the glands are unable to make the enough of some very important hormones (and instead make too much of another).
Control of the adrenal glands: the pituitary ‘switch’
The adrenal glands are controlled by the pituitary gland, a pea-sized gland at the base of the brain. It is the ‘master gland’ which directs many of the other glands. When the adrenal glands are not producing enough of their main hormone (cortisol), the pituitary tells them to make more by sending an adrenal-stimulating hormone. If the levels of adrenal-stimulating hormone remain elevated for a prolonged period, the adrenal glands grow larger. When too much cortisol reaches the pituitary switch is turned off and the adrenal glands are allowed to rest until the hormone levels return to normal again. Usually, the pituitary and the adrenal glands are perfectly balanced.
- Cortisol – this hormone is needed to protect the body from the effects of illness or injury. If a person with poorly functioning adrenal glands develops an illness such as tonsillitis, or receives a significant injury such as a broken leg, they could go into a state of ‘shock’ (severe illness with dangerously low blood pressure) unless cortisol or an equivalent medication (such as hydrocortisone) is given. More will be said about this later.
- Salt-retaining hormone – This controls salt balance in the body via the kidneys. Salt is important in our body and our organs by balancing fluid levels. In the absence of this hormone, salt is lost uncontrollably in the urine, leading to dehydration and impacting organ health (salt-lack).
- Androgen (male type sex hormone) – Both males and females have androgen. It is thought to aid growth in childhood and is responsible for people having features such as pubic hair.
- Not only are the adrenal glands each able to make all three hormones, but they make them from the same starting material – cholesterol. This can be made in the body but also found in the diet, in animal fats. To understand how the adrenal glands achieve this, look at the diagram on the next page.