What is Addison's disease?
Addison's disease is a condition in which your adrenal glands do not make enough of certain hormones. The condition is named after a Dr Thomas Addison who first described it in 1855. Addison's disease is rare. Just over 8,000 people in the UK have Addison's disease at any one time. Most cases first develop in people aged between 30 and 50. However, it can occur at any age.
What are the adrenal glands and what do they do?
You have two small adrenal glands that lie just above each kidney. Each adrenal gland has an outer part (adrenal cortex) and an inner part (adrenal medulla). Cells in the adrenal glands make various hormones. A hormone is a chemical which is made in one part of the body but passes into the bloodstream and has effects on other parts of the body.
Cells in the outer part of the adrenals (adrenal cortex) make the hormones cortisol and aldosterone. The amount of cortisol that is made is controlled by another hormone called adrenocorticotrophic hormone (ACTH). ACTH is made in a small gland that lies just under the brain (the pituitary gland). This in turn is stimulated by another hormone which is produced by another part of the brain called the hypothalamus. ACTH passes into the bloodstream, is carried to the adrenal glands, and stimulates the adrenal glands to make cortisol.
- Cortisol is a hormone that is vital for health. It has many functions which include:
- Helping to regulate blood pressure.
- Helping to regulate the immune system.
- Helping to balance the effect of insulin in regulating the blood sugar level.
- Helping the body to respond to stress.
- Aldosterone helps to regulate salts in the blood and helps to control blood pressure.
Cells in the inner part of the adrenals (adrenal medulla) make the hormones adrenaline (epinephrine) and noradrenaline (norepinephrine). These have various actions throughout the body.
What are the causes of Addison's disease?
Autoimmune Addison's disease
In Western Europe, more than 8 in 10 cases are due to an autoimmune disease. The immune system normally makes proteins called antibodies, which are sent into the bloodstream to attack bacteria, viruses, and other germs. In autoimmune diseases, the immune system makes antibodies against part or parts of your own body. In autoimmune Addison's disease, you make antibodies which attach to cells in the adrenal cortex. These destroy the cells which make cortisol and aldosterone. The adrenal medulla is not affected, so you still make adrenaline (epinephrine) and noradrenaline (norepinephrine). It is thought that something triggers the immune system to make these antibodies. The trigger is not known.
TB is an infection which usually affects the lungs. In some cases the infection can spread to, and gradually destroy, the adrenals. In the past this was the most common cause of Addison's disease. In some parts of the world where TB is still common, it remains the most common cause.
Other less common adrenal causes include:
- Other infections which can sometimes affect both adrenals (for example, meningitis, HIV).
- Cancers of other parts of the body, which can spread and destroy the adrenals.
- Rare hereditary conditions - for example, adrenoleukodystrophy (ALD) and congenital adrenal hyperplasia (CAH).
- Being critically unwell - for example, after a heart attack (myocardial infarction).
- Damage to the adrenal gland (for example, due to injury, surgery or radiotherapy).
- Medicines which occasionally can have an effect on production of adrenal hormones, such as ketoconazole, fluconazole and phenytoin.
Secondary causes of a low cortisol level
As mentioned, the amount of cortisol that you make in the adrenal glands is controlled by another hormone called ACTH. This is made in the pituitary gland. If you have a low level of ACTH, your adrenals make too little cortisol. Strictly speaking, this is not a condition of the adrenals, and is not classed as Addison's disease. However, it causes similar symptoms and is called secondary hypoadrenalism. Causes of a low ACTH level include:
- Some disorders of the pituitary gland, which can cause a lack of ACTH (along with other pituitary hormones). For example, tumours, injury, surgery, radiotherapy or infection.
- Some disorders of the hypothalamus, which in turn produces the hormone which stimulates ACTH. For example, tumours, injury, surgery, radiotherapy, or infection involving the hypothalamus.
- Long-term use of steroid medicines such as prednisolone. Steroid medicines are similar to cortisol. They are sometimes used to treat arthritis, cancer, and various other conditions. If you take a steroid medicine for several weeks or more, you stop making ACTH and cortisol, as the steroid medicine takes over the role of cortisol. If you suddenly stop taking the steroid medicine, it takes quite some time for the pituitary and adrenal glands to get back into the normal making of ACTH and cortisol. Therefore, if you stop the medicine suddenly, you have no cortisol or steroid medicine equivalent. You can then quickly develop symptoms similar to an Addisonian crisis (see below).
The rest of this leaflet deals only with autoimmune Addison's disease.
What are the symptoms of autoimmune Addison's disease?
In many cases the symptoms develop gradually over weeks or months
As the level of cortisol gradually falls you may develop one or more of the following:
- General weakness and becoming easily tired.
- Darkened areas of skin (pigmentation). The cause of this is probably due to the change in hormones which can affect the pigment cells in the skin. Pigment changes mainly occur on:
- Sun-exposed areas of skin.
- The creases of the hands.
- Gums and inside the mouth.
- Recent (rather than old) scars.
- Pressure points such as the elbows.
- Blood pressure which is low and falls further when you stand, which can make you dizzy.
- Being off your food.
- Loss of weight.
- Feeling sick and being sick (vomiting) from time to time.
- Tummy (abdominal) pains which may come and go.
- Diarrhoea or constipation which may come and go.
- Cramps and pains in muscles.
- Craving for salt or for salty foods and drinks.
- Menstrual periods in women may become irregular or stop.
The symptoms can be vague at first. For example, you may feel tired and not right, but it is difficult to say why. Also, most of the symptoms can be caused by other problems, and Addison's disease is rare. So, the condition may not be recognised for weeks or months after symptoms first begin.
Sudden (acute) symptoms develop in some cases (adrenal or Addisonian crisis)
If the level of cortisol falls to become very low you can become very ill in a short time. This is called an Addisonian crisis. In this situation symptoms include:
- Severe vomiting and diarrhoea.
- Pains in the back and abdomen.
- Lack of fluid in the body (dehydration).
- Low blood pressure.
You may become severely ill and may die if the cause of the symptoms is not diagnosed and treated quickly.
An Addisonian crisis may suddenly develop after a period of less severe symptoms (described above). The crisis is often triggered by another illness such as an infection or a stress such as a surgical operation. During these times your body needs extra cortisol. But, if you have Addison's disease you cannot make extra cortisol, and you may then quickly develop these crisis symptoms. In some cases an Addisonian crisis develops when there have not been any previous symptoms.
What tests are needed?
Blood tests may help point to Addison's disease. These include measurements of some of the salts in your body (sodium and potassium), sugar levels, calcium levels and morning cortisol levels. A one-off measurement of blood cortisol, however, may not be enough to diagnose Addison's disease. It may be low from time to time in normal people. Therefore, if Addison's disease is suspected, a special stimulation test is usually needed to confirm the diagnosis. The adrenal gland can be stimulated by an injection of a substance similar to ACTH. If the adrenals are normal, then blood samples taken shortly after this injection should show a rise in cortisol. If you have Addison's disease you do not have a rise in blood cortisol following the injection. The usual test performed in this way is called a Synacthen® test.
Once tests show you have a lack of adrenal hormones, there will be tests done to find out why. A blood test may detect antibodies which cause autoimmune Addison's disease. This is (as mentioned above) the most common cause. If this is found to be the case further tests will not be needed.
Other tests may be needed if it is thought that you have Addison's disease caused by other conditions such as TB, or a secondary cause of a low ACTH and cortisol level. This may involve further blood tests, X-rays or scans.
What is the treatment for autoimmune Addison's disease?
You need steroid medication to replace the cortisol which you no longer make. This is usually with a medicine called hydrocortisone which is very similar to cortisol.
The amount is usually about 15-30 mg each day. Some people need more than this and others less. The daily amount is broken up into two or three doses each day with a higher dose taken in the morning than in the evening. For example, you may be advised to take 15 mg in the morning and 10 mg early in the evening. Some people say they feel better taking the daily amount divided into three doses over the daytime. This dosing aims to mimic the normal pattern of cortisol levels in the body which are normally higher in the morning than in the evening. The last dose should be taken no less than four hours before bedtime. Your doctor will explain the exact dosing plan. There is a newer once-a-day option available, which may be suitable for some people.
The exact dose needed depends on factors such as your height, weight, sex and level of activity. You will be advised of the doses by your doctor. It may take a while to adjust the doses to the correct ones for you.
You will need to increase the amount of hydrocortisone you need per day in certain situations - see below.
You should never miss taking your medication. It is vital for your well-being.
Fludrocortisone is a substitute medicine for aldosterone. This helps to regulate blood pressure and blood salt level.
If you have an Addisonian crisis
This is a medical emergency. You will be given hydrocortisone injections, a drip of fluid to bring up your blood pressure and may need intensive care until the crisis is over. You will then need to continue taking hydrocortisone medication as detailed above.
Cortisol replacement - special circumstances
If you have Addison's disease, it is vital that you take the right amount of cortisol replacement (hydrocortisone) every day. Without this replacement medicine you can become very ill. So, some things to bear in mind:
If you are ill or need an operation
If you have an illness such as an infection, or an accident, or anything else causing major stress, such as an operation, you need extra hydrocortisone. Your doctor may advise you on some general "sick day rules" to follow. For example, this may include:
- If you have a high temperature (fever) of 37.5°C or more - double your normal dose. Triple the dose for fever of 39°C or more. Call a doctor if you have a fever of more than 40°C.
- If you have any serious injury - take 20 mg hydrocortisone immediately (in addition to your normal doses for the day).
- If you have diarrhoea, double your normal dose until it has settled.
- If you have been sick (vomited) once - take 20 mg hydrocortisone immediately after you vomit. Also, make sure you have plenty to drink to make sure you do not become lacking in fluid in the body (dehydrated).
- If you vomit twice or more - use an emergency injection of hydrocortisone (described below) and call a doctor for advice. Make sure that any doctor knows you have Addison's disease and this, in addition to the cause of the illness, needs attention.
- If you are about to have any operation, dental procedure, or medical procedure such as an endoscopy - you must make sure that the doctor, dentist or anaesthetist knows that you have Addison's disease. You will need extra doses of hydrocortisone.
Basically, for any illness, injury or operation, you need extra hydrocortisone. This can be taken as tablets but an emergency injection of hydrocortisone might be appropriate as an alternative, especially for situations such as a serious injury. And when you are ill, if you become dizzy or faint, this is a good indication that you might need a drip of fluid. Call a doctor immediately if this occurs and state that you have Addison's disease.
The Addison's disease self-help group website (details below) has a wealth of information about how to handle various situations. If you know what to do in different situations involving stress, trauma or illness, you can avoid an adrenal crisis.
Your repeat prescription - including stand-by emergency injections
Make sure you obtain your medication well in advance so that you never run out. Also, your doctor is likely to prescribe you some hydrocortisone injections for emergencies and show you how to use them. These are high-dose and are to be used in emergencies as described above. People with Addison's disease are entitled to free prescriptions. See your pharmacist for details.
If you go on holiday
Take ample supplies of your medication and emergency hydrocortisone injections. Make sure you have extra hydrocortisone, in case you need to double it for any reason. Consider taking a letter about your condition (see below.)
If you take part in strenuous sport or exercise
You will need extra hydrocortisone and fluids (for example, if you do a marathon). The amount can vary so take advice from your doctor.
If you work shifts or at night
The dosage of the hydrocortisone aims to replicate the normal variation in cortisol levels. This fluctuates with shift workers. Take advice from your doctor as to how to adjust the dose to suit your work schedule.
Some other points to consider
Consider wearing a bracelet and carrying a letter
You are strongly advised to wear a medical emergency identification bracelet or similar. This can alert people that you need hydrocortisone in case of emergencies. For example, if you are knocked out in a car crash and are not able to tell the doctor that you have Addison's disease. Apart from any other treatment, you will always need your hydrocortisone (or similar steroid replacement for cortisol). Also, consider carrying a letter or card with details of your usual and emergency treatment to show to any doctor you may see who is unfamiliar with Addison's disease. The Addison's Disease Self Help Group (see below) has multilingual cards that can be used for this purpose.
Tell a doctor if you are prescribed other medication
Some medicines used to treat other conditions can interfere with the medicines used to treat Addison's disease. For example, the combined oral contraceptive pill and hormone replacement therapy (HRT) used in the treatment of menopausal symptoms both interact with cortisone. The dose, therefore, may need adjusting. Always tell a doctor that you are being treated for Addison's disease if you are prescribed any other medicine.
'Thinning' of the bones (osteoporosis) may be more common in people with Addison's disease compared to the general population. Osteoporosis mainly affects older people, in particular women who are past the menopause. There is much that can be done throughout your life to help prevent the development of osteoporosis or to minimise its severity if it develops when you are older. For example, regular exercise, a good diet and not smoking will all help. Where necessary, medication may be advised if bone 'thinning' is detected. A special type of scan that measures bone density is used to detect osteoporosis. See separate leaflet called Osteoporosis for more details.
As mentioned above, if you have autoimmune Addison's disease, you have a higher-than-average chance of other autoimmune diseases developing. For example, thyroid problems, vitiligo, and pernicious anaemia - the most common being thyroid disorders, which are treatable. Therefore, tell your doctor if you develop any other unexplained symptom. You will normally have regular blood tests to check you have not developed any of these conditions.
Further help & information
Dr Tim Kenny
Dr Mary Harding
Dr John Cox