Addison's disease

Addison's disease (also known as chronic adrenal insufficiency, or hypocortisolism) is a rare endocrine disorder. It is estimated that it affects about 1 to 5 in 100,000 people. It occurs when the adrenal glands, seated above the kidneys, fail to produce enough of the hormone cortisol and, sometimes, the hormone aldosterone. Addison's disease refers to primary adrenal insufficiency occurs when the adrenal glands themselves are not dysfunctional; secondary adrenal insufficiency occurs when the pituitary gland does not produce enough adrenocorticotropic hormone (ACTH) to adequately stimulate the adrenal glands.

Table of contents

1 Signs and symptoms 1.1 Early signs 1.2 Addisonian crisis 2 Diagnosis 3 Pathyophysiology 4 Treatment 5 References

Signs and symptoms

Early signs

Addison's disease progresses slowly, and symptoms may not present or be noticed until some stressful illness or situation occurs. Common symptoms are:

• chronic fatigue that gradually worsens
• muscle weakness
• loss of appetite
• weight loss
• nausea/vomiting
• diarrhea
• low blood pressure that falls further when standing (orthostatic hypotension)
• areas of hyperpigmentation (darkened skin)
• irritability
• depression
• craving for salt and salty foods
• hypoglycaemia (worse in children)
• for women, menstrual periods that become irregular or cease

Addisonian crisis

An illness or accident can aggravate the adrenal problems and cause an Addisonian crisis in which the symptoms include:

• sudden penetrating pain in the legs, lower back or abdomen
• severe vomiting and diarrhea, resulting in dehydration
• low blood pressure
• loss of consciousness
• hypoglycemia

Untreated, an Addisonian crisis can be fatal. It is a medical emergency.

Diagnosis

In suspected cases of Addison's disease, one needs to demonstrate that adrenal hormone levels are low after appropriate stimulation with synthetic pituitary hormone. Once demonstrated, the cause of adrenal failure needs to be elucidated. The most common cause is autoimmune, and can easily be tested for with an assay for 21-hydroxylase antibodies. If there are no antibodies present, then infectious, or genetic causes should be sought. This may include imaging of the adrenal glands, tests for tuberculosis, HIV and searching for metastatic cancer.

Pathyophysiology

Eighty to ninety percent of cases of Addison's disease are due to autoantibodies directed against adrenal cells containing the enzyme 21-hydroxylase, an enzyme involved in the production of cortisol and aldosterone. The remainder of cases are due to tuberculosis, HIV, sarcoidosis, amyloidosis, hemochromatosis, metastatic cancer to the adrenal glands, adrenal haemorrhage and congenital hypoplasia. Addison's disease can be an expression of an autoimmune polyendocrine syndrome when autoimmune reactions against other organs are also present. In APS type 1, 70% suffer from Addison's disease, while in type 2, 100% do. Through these syndromes, Addison's is associated with hypothyroidism, diabetes mellitus (type 1),vitiligo, alopecia and celiac disease.

Treatment

Treatment for Addison's disease basically involves replacing the missing cortisol and, if necessary, providing replacement therapy for the missing aldosterone. Caution must be exercised when the person with Addison's disease has surgery or becomes pregnant.

References

• Addison's disease: adrenal insufficiency