Adrenal insufficiency is classified as primary or secondary. Primary adrenal insufficiency is known as Addison's disease. Addison's disease occurs when the adrenal glands are damaged and cannot produce enough of the hormone cortisol (hydrocortisone), and often the hormone aldosterone. Secondary adrenal insufficiency occurs when the pituitary gland in the brain fails to produce enough adrenocorticotropin hormone (ACTH). This leads to lack of production of cortisol in the adrenal glands.
The adrenal glands are located just above each kidney. Normally functioning adrenal glands work interactively with the hypothalamus and pituitary glands in the brain. The hypothalamus produces corticotropin releasing hormone, which stimulates the pituitary gland to produce ACTH. ACTH then stimulates the adrenal glands to produce cortisol and release it into the bloodstream. Cortisol is a steroid hormone that helps control the metabolism of fats, proteins, and carbohydrates. It also affects immune system functions and suppresses inflammatory reactions in the body.
The adrenal glands also produce aldosterone to help maintain blood pressure, water balance, and sodium and potassium balance. Addison's disease is considered rare. Onset of this disease may occur at any age.
Destruction of the adrenal glands due to an autoimmune response is the most common cause of the disease. Some cases of Addison's disease are caused by the actual destruction of the adrenal glands through cancer, infection, or other events. Other causes may include:
Tuberculosis infection of the adrenal glands
Inherited disorders of the endocrine glands
A lack of ACTH leads to secondary adrenal insufficiency. A common cause for this is suppression of ACTH through long-term use of steroids such as prednisone. Prednisone is often used to help patients with severe asthma, rheumatoid arthritis, and some other chronic conditions. Other causes include:
Pituitary gland tumors
Loss of blood flow to the pituitary
Surgical removal or radiation treatment of the pituitary
Surgical removal of parts of the hypothalamus
Mild symptoms of adrenal insufficiency/Addison's disease may only be apparent when the patient is under physical stress. The following are the most common symptoms. However, each individual may experience symptoms differently. Symptoms may include:
Dark skin (Addison's disease only)
Bluish-black discoloration around the nipples, mouth, rectum, scrotum, or vagina (Addison's disease only)
Lack of appetite
Low blood pressure
Low sugar levels (hypoglycemia)
In women, irregular or absent menstrual periods
If not treated, Addison's disease may lead to severe abdominal pain, extreme weakness, low blood pressure, kidney failure, and shock—especially when the patient is experiencing physical stress.
The symptoms of Addison's disease may resemble other conditions or medical problems. Always consult your doctor for a diagnosis.
In addition to a complete medical history and medical examination, diagnostic procedures for Addison's disease may include:
Various blood and urine tests to measure adrenal hormone levels
Radiology tests including X-ray, ultrasound, CT (computed tomography) scan or MRI (magnetic resonance imaging)
Treatment consists of replacing or substituting the hormones that are not being produced by the adrenal glands. This includes cortisol and, in Addison's disease, aldosterone.
Since Addison's disease can be life threatening, treatment often begins with administration of corticosteroids. Corticosteroids, such as prednisone, may be taken orally or intravenously, depending on the patient's condition. Usually the patient has to continue taking the corticosteroid the rest of his or her life. Treatment may also include taking fludrocortisone, a drug that helps maintain normal levels of sodium and potassium in the body.