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, but 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 adrenal cortex (the outer part of the adrenals) 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 the pituitary gland (a small gland that lies just under the brain). 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 adrenal medulla (inner part of the adrenals) make the hormones adrenaline and noradrenaline. These have various actions throughout the body.
What are the causes of Addison's disease?
Autoimmune Addison's disease
About 7 in 10 cases are due to an autoimmune disease. The immune system normally makes antibodies to attack bacteria, viruses, and other germs. In autoimmune diseases, the immune system makes antibodies against part or parts of the 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 and noradrenaline). It is thought that something triggers the immune system to make these antibodies. The trigger is not known.
If you have autoimmune Addison's disease you have a higher-than-average chance of other autoimmune diseases developing, such as thyroid problems, vitiligo, and pernicious anaemia.
TB is an infection which usually affects the lungs. In some cases the infection can spread to, and gradually destroy, the adrenals.
Other rare adrenal causes include:
- Other infections which can sometimes affect both adrenals.
- Cancers of other parts of the body, which can spread and destroy the adrenals.
- Rare hereditary conditions, eg adrenoleukodystrophy (ALD) and adrenomyeloneuropathy(AMN).
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 and tumours of the pituitary gland, which can cause a lack of ACTH (and other pituitary hormones).
- 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 auto-immune 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). These mainly occur on: sun-exposed areas of skin; the armpits; the nipples; the creases of the hands; inside the mouth; recent (rather than old) scars; pressure points such as the elbows. The cause of this is probably due to the change in hormones which can affect the pigment cells in the skin.
- Blood pressure which is low and falls further when you stand, which can make you dizzy.
- Being off your food and weight loss.
- Feeling sick and vomiting from time to time.
- Abdominal pains which may come and go.
- Diarrhoea or constipation which may come and go.
- Cramps and pains in muscles.
- Craving for salt, or salty foods and drinks.
- Menstrual periods in women which 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.
Acute (sudden) symptoms develop in some cases - an 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, dehydration, low blood pressure, and collapse. 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?
A one-off measurement of blood cortisol is not good 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 drug 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. Also, a blood test may detect antibodies which cause autoimmune Addison's disease.
(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.)
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.
The exact doses needed can depend on factors such as your height, weight and sex. 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. You may also be advised to take extra salt each day. (Note: don't eat liquorice root, as it may interfere with fludrocortisone medication. Most liquorice sweets are only liquorice-flavoured and can safely be eaten - but do check the list of ingredients. Real liquorice is also an ingredient of some cough medicines.)
Dehydroepiandrosterone (DHEA) replacement
DHEA is a hormone that is normally made by the adrenal gland. This hormone is not essential for life and the function of this hormone is not clear. People with Addison's disease lack this hormone. However, there has been debate as to the value of taking a replacement for this hormone; it may be prescribed by some specialists.
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 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 vomit once - take 20 mg hydrocortisone immediately after you vomit. Also, make sure you have plenty to drink to make sure you do not become 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.
Your repeat prescription - including stand-by emergency injections
Make sure you get your medication well in advance so that you never run out. Also, your doctor is likely to prescribe you some hydrocortisone injections 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.
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 bracelet, necklace or similar which 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 (details 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 and so the dose may need adjusting. Therefore, always tell a doctor that you are being treated for Addison's disease if you are prescribed any other medicine.
Osteoporosis (thinning of the bones) is 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, such as thyroid problems, vitiligo, and pernicious anaemia - the most common being thyroid disorders, which are normally treatable. Therefore, tell your doctor if you develop any other unexplained symptom.
Further help & information
Dr Tim Kenny
Dr Laurence Knott
Dr Adrian Bonsall