Addison’s disease .

Addison’s disease (primary adrenal insufficiency) is caused by destruction of the adrenal cortex. This results in reduced production of glucocorticoids (such as cortisol), mineralocorticoids (such as aldosterone), and adrenal androgens (such as dehydroepiandrosterone).

Adrenal insufficiency may also be caused by long-term administration of corticosteroids or disorders of the hypothalamus or pituitary gland, but this is not Addison’s disease.

In the developed world, Addison’s disease is most commonly caused by autoimmune disease. Worldwide, tuberculosis is the most common cause of Addison’s disease.

Addison’s disease is rare. About 8,400 people are currently diagnosed with Addison’s disease in the UK.

Diagnosis of Addison’s disease is often delayed because symptoms are non-specific, common, and overlap with those of many other conditions.

The person with Addison’s disease may present with a sudden crisis precipitated by intercurrent infection or stress. Features include hypotension, hypovolaemic shock, acute abdominal pain, low-grade fever, and vomiting.

Addison’s disease should also be considered if the person has persistent, non-specific symptoms, such as: fatigue; hyperpigmentation; gastrointestinal symptoms; cravings for salt, soy sauce, or liquorice; musculoskeletal symptoms; or postural dizziness due to hypotension.

The possibility of Addison’s disease should also be considered in people with: hypothyroidism whose symptoms worsen when thyroxine is started; type 1 diabetes with recurrent unexplained hypoglycaemic episodes; other autoimmune diseases; or low sodium and high potassium levels on blood biochemistry.

In adults, if adrenal insufficiency is suspected on the basis of clinical features, a serum cortisol level and urea and electrolytes should be requested.
As a general guide:
If the serum cortisol level is less than 100 nanomol/L, the person should be admitted to hospital or referred urgently to an endocrinologist. Adrenal insufficiency is highly likely.
If the serum cortisol level is 100–500 nanomol/L, the person should be referred to an endocrinologist for further investigations.
If the serum cortisol level is more than 400 nanomol/L, the diagnosis of Addison’s disease is unlikely.
If the person is acutely unwell or hypotensive, urgent advice should be sought from an endocrinologist. Serum cortisol values are not reliable, as they increase during illness.

The diagnosis of Addison’s disease is usually confirmed in secondary care. An adrenocorticotrophic hormone stimulation (Synacthen®) test should be done.

See below for DD and traetment.

G Mohan.