Adrenal insufficiency is a term used to describe the failure of the adrenal glands to secrete sufficient amounts of several hormones that are critical to the normal function of the body. This insufficiency can have many causes such as genetic factors, autoimmune disease, congenital disorder, surgery, or radiotherapy.
Definition & Facts
In adrenal insufficiency, the paired adrenal glands (also known as the suprarenal glands), which are positioned atop each kidney, fail to secrete sufficient amounts of the steroid hormones such as cortisol and aldosterone. They may also fail to meet the body’s needs for a different class of steroid hormones known as mineralocorticoids.
The best-known form of adrenal insufficiency is Addison’s disease, which is chronic in nature but responds well to hormone replacement therapy in which steroids such as cortisone are administered orally or by injection. Addison's disease is also called primary adrenal insufficiency. Secondary adrenal insufficiency occurs when the pituitary gland fails to produce enough adrenocorticotropic hormone (ACTH) which triggers the adrenal glands to make cortisol.
Symptoms & Complaints
Other signs of adrenal insufficiency can include vomiting, loss of appetite, hyperpigmentation, and vitiligo. A classic sign of the Addison’s disease variant of adrenal insufficiency is an abnormal tanning of the skin that is usually seen in the skin creases (e.g. the palms of the hands or elbow areas).
The causes of adrenal insufficiency are generally placed into one of three broad categories:
- Primary adrenal insufficiency: due to to either a structural abnormality of the adrenal glands (normal tissue is replaced by tumor growth or, in rare cases, the glands did not form properly before birth), an autoimmune disease, or an unknown cause.
- Secondary adrenal insufficiency: primarily caused by long-term administration of exogenous (from outside the body) steroids or, less commonly, an abnormal growth affecting the pituitary gland. The pituitary is often called the body’s master gland because it releases its own special hormones that signal the body to produce other other hormones.
- Tertiary adrenal insufficiency: caused by a lesion of an area at the base of the brain affecting the hypothalamus, which interferes with the release of corticotropin-releasing hormone (CRH).
Diagnosis & Tests
The diagnosis of adrenal insufficiency is usually suggested by presentation of symptoms, medical history and family history. Once a diagnosis of adrenal insufficiency is suspected, initial laboratory testing will include a full biochemistry panel, hormonal assays, immunologic studies, and probably will include glucose tolerance testing and clinical urine tests for the presence of abnormal metabolic byproducts and the presence of heavy metals.
Radiological exams such as a complete abdominal ultrasound can be used to evaluate the size and shape of the adrenal glands as well as the status of the other abdominal organs, but computed tomography (CT) scans and/or magnetic resonance imaging (MRI) studies will probably be necessary for a complete anatomic survey of the adrenals.
If a tumor of the pituitary or the hypothalamus is suspected, MRI studies and probably angiography (blood vessel X-rays that using a special dye) will be needed to confirm the diagnosis and for treatment planning purposes.
Treatment & Therapy
Treatment of adrenal insufficiency is directed toward first replacing the hormones that are missing and then to repairing the condition that was responsible. In the case of primary adrenal insufficiency this is accomplished by giving the patient supplemental hydrocortisone or prednisone by injection or orally until the presenting symptoms subside and then instituting a maintenance dosage while closely monitoring the response.
If an autoimmune cause of the insufficiency is documented, treatment of the primary insufficiency is essentially the same as the treatment for the cause of the insufficiency: externally-administered corticosteroids with the possible addition of low-doses of medications that block portions of the body’s immune response.
When a secondary adrenal insufficiency has been diagnosed, the initial treatment is the same as for a primary insufficiency: cortisone, along with the correction of any underlying fluid and electrolyte problems while a search is made for the cause of the adrenal insufficiency. Cases of a benign tumor called an adenoma may respond quite well to radiation treatment and possibly to a freezing of the tumor called cryosurgery.
Prevention & Prophylaxis