The adrenals are triangular glands that sit atop each kidney. They secrete hormones that help the body deal with stress, maintain appropriate levels of glucose in the bloodstream, stimulate the kidneys to maintain appropriate fluid and electrolyte balance and influence sexual development. Adrenal insufficiency is a condition in which the adrenals do not produce appropriate levels of these hormones, especially cortisol and aldosterone.
Anatomy
The adrenal gland is divided into a cortex and a medulla. The inner medulla secretes the hormones epinephrine and norepinephrine, which help the body's response to stress--the so-called "fight-or-flight" response--by increasing heart rate, blood pressure and blood flow to the muscles. The outer cortex secretes the hormones cortisol and aldosterone. Adrenal insufficiency results when at least 90 percent of the cortex is destroyed, which can occur as a result of an autoimmune process, in which the body slowly destroys the adrenal tissue; infections, such as tuberculosis or fungal infections; cancer; bleeding; or AIDS.
Hormone Function
Cortisol helps control the levels of glucose in the bloodstream, helps modulate the body's immune response to infections and plays an important role in the management of stress. Aldosterone helps maintain the body's fluid balance by acting on the kidneys to absorb sodium and water. Aldosterone also helps regulate blood pressure.
Types
Adrenal insufficiency falls into two categories, according to the National Endocrine and Metabolic Diseases Information Service. Primary adrenal insufficiency, also known as Addison's disease, occurs from destruction of the adrenal cortex. Secondary adrenal insufficiency occurs when the brain fails to secrete ACTH, the hormone that stimulates the adrenal gland's functions. This can happen if a person takes steroids for a long time and suddenly stops taking them, as the constant level of steroids blocks the release of ACTH. It also can happen during surgery to remove pituitary tumors that secrete excess ACTH, or it can occur as a result of conditions in which the pituitary shrinks.
Symptoms
Children with adrenal insufficiency usually experience chronic muscle weakness and fatigue, nausea and vomiting, loss of appetite and weight loss. They have low blood pressure that gets worse when they stand, making them dizzy. They can be irritable and feel depressed. Because of the lack of aldosterone, which regulates sodium absorption in the kidneys, these children are always thirsty and crave salt. They have low blood sugar because of low cortisol levels. Children with Addison's disease have hyperpigmentation, or darkening of the skin in non-exposed areas, skin folds and scars.
Warning
An Addisonian or adrenal crisis occurs when symptoms of adrenal insufficiency suddenly worsen. The body lacks cortisol and cannot fight off infections or even mild illnesses, as cortisol is necessary in stressful situations. An adrenal crisis is a life-threatening emergency that requires prompt medical attention. Symptoms of an adrenal crisis include severe vomiting and diarrhea, dehydration, low blood pressure, abdominal pain and confusion. If untreated, a child in an adrenal crisis could fall into a coma, have hard-to-control seizures, go into shock and die.
Treatment
Treatment of adrenal insufficiency involves substituting the missing hormones, cortisol and aldosterone. Cortisol is replaced with synthetic steroids such as hydrocortisone and prednisone, while aldosterone is replaced with a medicine called fludrocortisone acetate. During an adrenal crisis, timely administration of intravenous fluids and steroids, as well as correction of blood sugar and potassium levels, is vital.
