Addison’s disease is one of three types of adrenoleukodystrophy (ALD), a genetic condition caused by a mutation in the ABCD1 gene. This mutation results in little or no adrenoleukodystrophy protein (ALDP) being produced. This protein is normally required for the transport and breakdown of compounds known as very long-chain fatty acids (VLCFA) inside cells. When ALDP cannot function properly, VLCFAs build up inside cells. This can cause the protective sheath around nerve cells, called the myelin sheath, to become damaged and the nerve cells to die and cause damage to the adrenal glands. The adrenal glands sit on top of the kidneys and are responsible for the production of many vital hormones, including the stress hormone cortisol.
In some cases, the disease affects only the adrenal glands, where the buildup of VLCFA plugs the glands and causes structural damage. This is called Addison’s disease. The injury caused to adrenal glands results in deficient production of cortisol and aldosterone. This adrenal or adrenocortical insufficiency affects various body functions, including stress response.
Addison’s disease constitutes around 10 percent of all ALD cases.
The symptoms of Addison’s disease develop gradually. They can be very unspecific and vary from patient to patient. Some of the common symptoms reported in the initial stages include:
- Skin abnormalities such as hyperpigmentation (darkening of the skin) and vitiligo (white patches on the skin)
- Low blood pressure (hypotension)
- Syncope (fainting)
- Muscle pain and spasms
- Gastrointestinal problems such as abdominal pain, nausea, and vomiting
- Psychological issues (depression and anxiety)
- Behavioral issues such as poor concentration
Women may experience changes in their menstrual cycle, decreased libido, and hair loss.
Acute adrenal failure or Addisonian crisis can occur in rare instances when there is a rapid onset of the condition, usually triggered by stress such as an accident or infection. If left untreated, Addisonian crisis can lead to shock or kidney failure. The symptoms include severe pain in the back, legs, or stomach, sudden weakness, low blood sugar, vomiting, diarrhea, hypotension, and fainting.
Blood tests to detect levels of sodium, potassium, and cortisol are used to diagnose Addison’s disease. A combination of low sodium, high potassium, and low cortisol is an indicator of adrenal insufficiency.
Based on the patient’s family and medical history, further tests will be needed to confirm the diagnosis and differentiate Addison’s only form of ALD from other conditions.
Medical imaging techniques such as MRI or CT may also be used to visualize adrenal gland injury.
In Addison’s only type of ALD, the adrenal glands produce inadequate amounts of either cortisol, aldosterone, or both. Based on blood tests, a doctor can determine whether one or both of these steroid hormone replacements is needed.
Cortisol is commonly replaced by oral glucocorticoids such as prednisone, hydrocortisone, and dexamethasone. Oral hydrocortisone (Cortef by Pfizer) is the most commonly used glucocorticoid. Side effects associated with glucocorticoid use include weight gain.
Oral mineralocorticoids are used to treat aldosterone deficiency. Fludrocortisone (Florinef) is a commonly used mineralocorticoid. Aldosterone affects the salt and water balance in the body. Intake of fludrocortisone may increase the urge for salty food. Doctors may recommend an increase in salt intake while on mineralocorticoid therapy.
An Addisonian crisis requires hospitalization and is treated with an injection of glucocorticoids into the bloodstream or a muscle. Low blood sugar and low sodium levels are characteristic of Addisonian crisis. Patients may also need fluid injection into the bloodstream with salt and sugar as a supportive treatment.
Other conditions causing Addison’s disease
Adrenal gland injury may also occur in other conditions and result in abnormal levels of hormone production. In addition to ALD, Addison’s disease is also reported in:
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