What is Addison’s disease?
Adrenal insufficiency or Addison’s disease is a rare disorder that occurs in all age groups and both sexes and can be life-threatening. The most characteristic symptom is the orange/brown discoloration (hyperpigmentation) of the skin, especially in the creases of the hands and the oral mucosa.
What causes Addison’s disease?
Addison’s disease occurs when the adrenal glands, located just above the kidneys, do not produce enough of certain hormones (too little cortisol and often, too little aldosterone).
In 70% of cases, it is caused by an autoimmune reaction, when the body’s immune system mistakenly attacks the adrenal glands.
Other causes can include tuberculosis, repeated infections, especially fungal infections, spread of cancer from another area of the body to the adrenal glands, bleeding into the adrenal gland or rare genetic diseases such as X-linked adrenoleukodystrophy.
How is Addison’s disease diagnosed?
Symptoms usually develop gradually over time and are usually vague, which often leads to delays in diagnosis.
Diagnosis is based on blood tests, which show cortisol deficiency.
However, if blood cortisol levels do not confirm the diagnosis, the most definitive way to diagnose Addison’s disease is through an ACTH-stimulation test. This test examines how cortisol reacts to an ACTH injection (a hormone that stimulates the adrenal gland to produce cortisol). In normal situations, cortisol levels in the blood would increase after ACTH injection. In patients with Addison’s disease, the adrenal glands cannot respond to ACTH stimulation, and cortisol levels remain low.
Other tests that may be performed include:
- Insulin-induced hypoglycaemic test: After insulin injection, blood sugar levels and cortisol levels are measured at different time points. In patients with normal adrenal function, cortisol levels will rise when glucose levels falls. In patients with Addison’s disease, the adrenal glands won’t make enough cortisol and cortisol levels will be low.
- CT scan/MRI/ultrasound of the adrenal gland.
What are the signs and symptoms of Addison’s disease?
Symptoms vary from one individual to another:
- Chronic fatigue
- Hyperpigmentation (darkening of the skin)
- Weight loss and decreased appetite
- Abdominal pain
- Muscle or joint pain
- Low blood pressure, even fainting
- Low blood sugar (hypoglycaemia)
- Craving salty foods
- Nausea, diarrhoea or vomiting
- Irritability and depression
- Irregular or no menstrual periods
How is Addison’s disease treated?
Addison’s disease cannot be cured, but it can be treated. Treatment involves replacement therapy: corticosteroids and mineralocorticoids are taken to compensate for what the body does not produce itself. The dose is adjusted to the patient’s needs. In most cases, the medicine must be taken for life. Symptoms usually disappear when treated.
In case of illness or surgery/accident, hence in situations where the body produces more cortisol, the corticosteroid dose has to be increased. If this is not done or if corticosteroid doses are skipped, patients are at risk of developing a life-threatening Addisonian crisis, which requires immediate administration of high dose corticosteroids (im/iv/rectal) and an infusion to stabilise blood salts and blood pressure.
It is therefore important for patients to be well-trained and to keep an emergency card with them that explains their condition and what to do in case of an Addisonian crisis.