Adrenal Insufficiency: An Introduction
Adrenal insufficiency is a medical condition in which the adrenal glands stop making hormones important for certain bodily functions. Adrenal insufficiency is characterized by weight loss, muscle weakness, fatigue, low
blood pressure, and sometimes darkening of the skin in both exposed and non-exposed parts of the body.
There are two general types of adrenal insufficiency:
Adrenal insufficiency occurs in all age groups and afflicts men and women equally.
Understanding the Adrenal Glands
There are two adrenal glands, one above each kidney in the back of the upper abdomen. The adrenal glands are also called the suprarenal glands. The inside layer of the adrenal gland is called the adrenal medulla. The adrenal medulla produces epinephrine (adrenaline). The outside layer is called the adrenal cortex. The cells in the adrenal cortex make important hormones that help the body function properly. The two hormones are cortisol and aldosterone.
Cortisol
Cortisol belongs to a class of hormones called glucocorticoids, which affect almost every organ and tissue in the body. Scientists think that cortisol has possibly hundreds of effects in the body. Cortisol's most important job is to help the body respond to stress. Among its other vital tasks, cortisol helps:
- Maintain blood pressure and cardiovascular function
- Slow the immune system's inflammatory response
- Balance the effects of insulin in breaking down sugar for energy
- Regulate the metabolism of proteins, carbohydrates, and fats
- Maintain proper arousal and sense of well-being.
Because cortisol is so vital to health, the amount of cortisol produced by the adrenals is precisely balanced.
Like many other hormones, cortisol is regulated by the brain's hypothalamus and the pituitary gland, a bean-sized organ at the base of the brain. First, the hypothalamus sends "releasing hormones" to the pituitary gland. The pituitary responds by secreting hormones that regulate growth and thyroid and adrenal function, and sex hormones such as estrogen and testosterone. One of the pituitary's main functions is to secrete ACTH (adrenocorticotropin), a hormone that stimulates the adrenal glands. When the adrenals receive the pituitary's signal in the form of ACTH, they respond by producing cortisol. Completing the cycle, cortisol then signals the pituitary to lower secretion of ACTH.
Aldosterone
Aldosterone belongs to a class of hormones called mineralocorticoids, also produced by the adrenal glands. Aldosterone helps maintain blood pressure and water and salt balance in the body by helping the kidney retain sodium and excrete potassium. When aldosterone production falls too low, the kidneys are not able to regulate salt and water balance, causing blood volume and blood pressure to drop.
Causes of Adrenal Insufficiency
Failure to produce adequate levels of adrenal hormones can occur for different reasons. The problem may be due to a disorder of the adrenal glands themselves (
primary adrenal insufficiency) or to inadequate secretion of ACTH by the pituitary gland (secondary adrenal insufficiency).
Symptoms of Adrenal Insufficiency
Given the importance of adrenal gland hormones, people with adrenal insufficiency can have a number of different adrenal insufficiency symptoms. The symptoms a person with adrenal insufficiency experiences will be affected by:
- The hormones that are deficient
- The level of hormone deficiency
- The cause of adrenal insufficiency
- Other stresses on the body.
Diagnosing Adrenal Insufficiency
In its early stages, it can be difficult to make an adrenal insufficiency diagnosis. After asking a number of questions and performing a physical exam, the doctor may recommend certain tests as part of making an adrenal insufficiency diagnosis. These adrenal insufficiency tests can include:
- ACTH stimulation test
- CRH stimulation test
- ACTH and cortisol blood levels
- Abdominal x-rays
- CT scan.
Treatment Options for Adrenal Insufficiency
In most cases, there is no adrenal insufficiency cure. However, adrenal insufficiency can be controlled with medications. Treatment for adrenal insufficiency involves replacing, or substituting, the hormones that the adrenal glands are not making.
Most people with adrenal insufficiency should expect to lead healthy lives with a normal life expectancy.
Because the symptoms of adrenal insufficiency progress slowly, they are usually ignored until a stressful event like an illness or an accident causes them to become worse. This is called an
addisonian crisis, or acute adrenal insufficiency. In most cases, symptoms are severe enough that patients seek medical treatment before a crisis occurs. However, in about 25 percent of patients, symptoms of adrenal insufficiency first appear during an addisonian crisis.
An addisonian crisis can cause life-threatening complications unless immediate treatment is provided.
Living With Adrenal Insufficiency
Taking medications is a critical part of adrenal insufficiency treatment. It is also very important for people to understand their disease and situations that can affect their hormone levels. For more information about living with adrenal insufficiency, click on any of the following eMedTV articles:
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