Diagnosis - Addison's disease

To help diagnose Addison’s disease, your GP will first ask about your symptoms and review your medical history.

Your GP is likely to ask if anyone in your family has an autoimmune disorder. This is a condition caused by a problem with their immune system.

Your GP will examine your skin for any evidence of brownish discolouration (hyperpigmentation).

Discolouration often appears in certain areas, such as:

• where skin creases on your palm
• in your elbow crease
• on any scars
• your lips and gums

But, hyperpigmentation doesn't occur in all cases of Addison’s disease.

You'll also be tested for low blood pressure (hypotension). This will be done while you're lying down and again shortly after you stand up. This is to see whether you have postural or orthostatic hypotension. This is low blood pressure when you change position.

Blood tests

If Addison’s disease is suspected, blood tests will be carried out. These are to measure the levels of sodium, potassium and cortisol in your body. A low sodium, high potassium or low cortisol level may indicate Addison’s disease.

You may need to see a hormone specialist (endocrinologist).

They can test your blood for:

• a low level of the hormone aldosterone
• a high level of adrenocorticotrophic hormone (ACTH)
• a low level of glucose (sugar used for energy)
• positive adrenal antibodies (antibodies designed to attack the adrenal gland)

Any of the above could be a sign of Addison’s disease.

Synacthen stimulation test

You may need to have a synacthen stimulation test to confirm a diagnosis of Addison's disease. This is done if cortisol in your blood is low, or your symptoms strongly suggest Addison’s disease.

Your GP may refer you to an endocrinology unit (a unit that specialises in the study of hormones) for the test. How urgently you're referred depends on how severe your symptoms are.

How it works

Synacthen is a man-made (synthetic) copy of the adrenocorticotrophic hormone (ACTH). ACTH is naturally produced by the pituitary gland. The pituitary glad is a pea-sized gland below the brain. ACTH encourages the adrenal glands to release the hormones cortisol and aldosterone.

When synacthen is administered, the adrenal glands should respond in the same way as they would to ACTH. They should release cortisol and other steroid hormones into the blood.

A blood sample will be taken and tested for cortisol, before an injection of synacthen is given into your arm. After 30 and 60 minutes, a further blood sample will be taken for cortisol measurement.

If the ACTH level is high, but the cortisol and aldosterone levels are low, it's usually confirmation of Addison’s disease.

Thyroid function test

Your thyroid gland may also be tested to see if it's working properly. Your thyroid gland is found in your neck. It produces hormones that control your body's growth and metabolism.

People with Addison’s disease often have an underactive thyroid gland. This is known as hypothyroidism. It means the thyroid gland does not produce enough hormones. By testing the levels of certain hormones in your blood, your endocrinologist can see if you have hypothyroidism.

Scans

In some cases, your specialist may refer you for a scan of your adrenal glands. This could be a computerised tomography (CT) scan or a magnetic resonance imaging (MRI) scan.

Diagnosis during an adrenal crisis

If Addison’s disease is left untreated, it eventually leads to an adrenal crisis. This is where the symptoms of Addison’s disease appear quickly and severely.

During an adrenal crisis, there's not enough time to perform a synacthen stimulation test to confirm Addison’s disease.

If possible, blood will be taken and tested for any of the abnormalities listed above. While you're waiting for the results, treatment may be started. This involves steroid injections and fluids containing salt and glucose.