What is gout?
Gout is a form of arthritis which can be intensely painful; and it's caused by having sodium urate crystals in your joints. These may be present for years without you knowing they're there, but on occasions they can trigger an attack of gout.
Attacks of gout usually come on very quickly, often during the night. Doctors describe this sudden development of symptoms as 'acute'.
At one time it was thought that gout was caused simply by overeating and drinking too much alcohol. While this can make attacks of gout more likely, it's not the whole story.
Gout is caused by chemical processes that take place in your body. A substance called urate builds up, sometimes because your kidneys aren't able to get rid of it quickly enough. Over a period of time this leads to urate crystals forming in and around your joints.
Once there are a lot of crystals in your joints some of them can trigger a sudden painful episode of severe joint inflammation ('attack') which usually settles back to appear normal within a week. If untreated these attacks get more common and spread to involve new joints.
Who gets gout?
Gout is the most common type of inflammatory arthritis, affecting 2.5% of adults in the UK. It affects more men than women and can affect men of any age. Women rarely develop gout before the menopause.
It gets more common with increasing age in both men and women, affecting 15% of men and 6% of women over the age of 75. Gout has been getting more common in recent decades in many countries, including the UK. This is mainly because we are living longer, and more people are getting overweight or obese.
Urate crystals cause inflammation, meaning the affected joint becomes:
- intensely painful
The skin over the affected joint often appears shiny and may peel.
Attacks typically affect the big toe and usually start at night. The symptoms develop quickly and are at their worst within 12-24 hours of first noticing anything is wrong.
Any light contact with the affected joint is painful, even the weight of a bedsheet or wearing a sock can be unbearable.
Gout most often causes symptoms in the big toe, but other joints which may also be affected include:
- joints in the feet
If several joints are inflamed at once this is called polyarticular gout. It’s very rare to have gout in joints towards the centre of the body such as the spine, shoulders or hips.
Urate crystals can also collect outside the joints and may even be seen under the skin, where they form small, firm white lumps called tophi. These aren’t usually painful but sometimes they break down and discharge pus-like fluid containing gritty white material, the urate crystals themselves.
Gout occurs in people who have levels of urate in their blood that are persistently above a critical level which allows urate crystals to form. About two thirds of the urate in our bodies comes from the breakdown of purines which are naturally present in the cells of our bodies. The other third comes from the breakdown of purines in some foods and drinks.
Having urate in your blood doesn’t mean you’ll definitely develop gout, it’s normal and healthy to have some urate in the bloodstream. When urate levels start to build up, your body usually gets rid of any excess urate through your kidneys into your urine; however, if your body is making too much urate or your kidneys are unable to remove enough urate, then urate levels start to rise. If the level goes above a certain point (the saturation point), it’s possible for urate to form crystals of sodium urate.
These crystals mainly form in and around joint tissues, especially joints at the ends of your legs and arms, such as your finger and toe joints.
The diagram above shows a joint with urate crystals. The crystals gradually build up in the cartilage and other joint tissues over years. You will not know this is happening. When there are a lot of crystals in your joints some of them can spill out into the joint cavity (the space between the bones). This process is called crystal shedding. The hard, needle-shaped crystals touch the soft lining of the joint (the synovium) and make it very inflamed very quickly.
The inflammation process breaks down the crystals that have become loose inside the joint, and the attack gradually settles over a few days or weeks, depending on how many crystals spilled out.
Apart from causing sudden attacks of inflammation, a build-up of crystals can eventually lead to tophi forming in and around your joints. These hard tophi can grow and cause pressure damage to your cartilage and bone. This is just like the damage caused by osteoarthritis and can cause more regular, daily pain when you use the affected joints. At this stage the condition is often called chronic tophaceous gout. Some tophi may be seen and easily felt under the skin, but by this time the unseen part of the tophi in your joints and deeper tissues are usually quite extensive.
Several factors can affect the level of urate in your body:
- The genes you’ve inherited may make it more likely that your kidneys don’t flush urate out of your body as well as they should, even though your kidneys are otherwise completely normal and healthy. This is the most common cause, especially when there are several family members affected.
- The bigger the body the more urate is produced each day, so if you’re overweight or obese it could cause your body to make more urate than your kidneys can get rid of.
- If you have high levels of cholesterol and fats in your blood (a condition called hyperlipidaemia), high blood pressure or late-onset (type 2) diabetes, your kidneys won’t be able to get rid of urate as well as they should, so all these conditions tend to be linked with raised urate levels. This combination of problems is often called metabolic syndrome.
- Kidney disease may mean that your kidneys aren’t able to process urate as well as they should.
- Some tablets such as diuretics (water tablets) reduce your kidneys’ ability to get rid of urate effectively.
- Rarely, if you have a chronic blood disorder that causes your body to produce too many blood cells, the level of urate produced by the breakdown of those cells may be higher than your kidneys can cope with.
Where a particular cause can be identified (such as kidney disease or regular use of diuretics), the condition is called secondary gout. However, most gout is primary and is usually due to a combination of factors, for example, through having inherited kidneys that aren’t very good at getting rid of urate and then becoming overweight.
If you’re prone to gout and have urate crystals in your joints, several things can encourage urate crystals to shake loose from your cartilage and trigger an acute attack. These can include:
- a knock or injury to the affected joint
- an illness, such as pneumonia or flu, that makes you feverish
- an operation, this also puts your temperature up a little
- overeating and drinking too much alcohol
Similar attacks can be caused by a condition called acute calcium pyrophosphate crystal arthritis (acute CPP crystal arthritis), which was sometimes previously called ‘pseudogout’. In this type of arthritis it’s calcium crystals that are deposited in joint cartilage rather than urate crystals. Acute CPP crystal arthritis affects the knee and other joints more than the big toe and is most common in people with osteoarthritis.
You may be more at risk of gout attacks if any of your parents or grandparents had it.
How will gout affect me?
Attacks can vary from person to person. Some people only have an attack every few years, while others have attacks every few months. In time, though, attacks tend to happen more often and new joints are affected.
Although acute attacks of gout are very dramatic, the inflammation goes down fairly quickly and the attacks themselves probably don’t cause long-term joint damage.
However, a continued build-up of urate crystals and formation of hard tophi can damage your cartilage and bone, leading to long-term (chronic) arthritis.
With modern treatments and possibly some changes to your diet and lifestyle, this type of damage can usually be prevented by bringing urate levels in your tissues down below the point at which crystals form.
Lowering your urate levels will prevent new crystals forming and slowly break down the crystals that are already there. It may take as long as two to three years of treatment to completely clear your body of urate crystals, but once they’re gone then the risk of acute attacks of gout and of further joint damage from tophi is removed.
Because gout is associated with metabolic syndrome, you should pay special attention to your cholesterol levels, blood pressure and diabetes. If these are treated effectively it can help reduce your urate levels.
As well as the threat of causing attacks of gout, persistently high urate levels can lead to other health concerns. For example:
- High urate levels can cause inflammation and furring of the lining of arteries and lead to increased risk of heart disease (for example, angina, heart attacks, atrial fibrillation, heart failure) and stroke.
- The crystals in your joints can cause long-term low-grade inflammation in between the acute attacks without you having any symptoms.
- High levels of urate can make chronic kidney disease worse.
- There is growing evidence that high urate levels increase the risk of cancers, especially prostate cancer.
Having acute attacks and eventually chronic joint symptoms due to gout is bad enough, but our increasing recognition of these additional health problems has made us realise that gout is a potentially serious condition that needs to be treated appropriately and not ignored.
A diagnosis of gout is often based on your symptoms and an examination of your joints, but your doctor may suggest you have some tests.
A blood test can measure the amount of urate in your blood. The critical serum level of urate (the saturation point) is around 360 μmo/L (equivalent to 6 mg/dl). This is within the normal range for men, and for older women, so being informed that your blood test is ‘within normal limits’ is irrelevant – you need to know if it is above or below this critical level. A raised level of urate strongly supports a diagnosis of gout but can’t confirm it – not everyone with a raised level of urate will develop crystals in their joints, and it’s possible for urate levels in the blood to be normal at the time of an acute attack.
X-rays of joints will reveal joint damage if you have long-standing and poorly controlled gout. However, x-rays are rarely helpful in confirming the diagnosis because they’re usually normal in the early years of having gout. Ultrasound of joints can be used to detect earlier signs of gout, and can be useful where the diagnosis is uncertain.
Synovial fluid examinations involve taking fluid samples from a joint through a needle and examining them under a microscope for urate crystals. This test can confirm the diagnosis but isn’t always practical. It can be difficult and sometimes uncomfortable to draw fluid from a small joint such as the big toe. However, it may be possible to identify a few crystals in a sample taken from your knee, even if you’ve not yet had an attack of gout there. A fine needle inserted into a tophus under your skin can also be used to identify urate crystals.
There are two main aspects to the treatment of gout:
- treating the acute attack of inflammation when one or more joints are very inflamed and painful
- ongoing treatment to reduce the level of urate in your blood and to get rid of urate crystals.
Treatments for acute attacks
The two most commonly used drug treatments for acute attacks of gout are non-steroidal anti-inflammatory drugs (NSAIDs) and colchicine.
Non-steroidal anti-inflammatory drugs (NSAIDs)
Acute attacks of gout are often treated with oral non-steroidal anti-inflammatory drugs (NSAIDs), which can ease pain and possibly reduce some of the inflammation. Examples include ibuprofen, naproxen and etoricoxib.
Like all drugs, NSAIDs can sometimes have side-effects, but your doctor will take precautions to reduce the risk of these – for example, by prescribing the lowest effective dose for the shortest possible period of time.
NSAIDs are more effective the closer you take them to the onset of an attack of gout.
NSAIDs can cause digestive problems (stomach upsets, indigestion, or damage to the lining of the stomach) so NSAIDs should be prescribed along with a drug called a proton pump inhibitor (PPI), which will help to protect your stomach.
NSAIDs also carry an increased risk of heart attack or stroke. Although the increased risk is small, your doctor will be cautious about prescribing NSAIDs if there are other factors that may increase your overall risk – for example, smoking, circulation problems, high blood pressure, high cholesterol or diabetes.
If you're on some other medication, including water tablets or warfarin, or if you have other medical conditions, such as chronic kidney disease, it may mean that you shouldn't take an NSAID, but your doctor will advise you on this.
Managing your symptoms
Healthy lifestyle choices
There are a number of changes you can make to your diet and lifestyle to help ease attacks of gout. The most useful things you can do are:
- losing weight if you’re overweight or obese
- reducing the foods you eat which are high in purines
- avoiding excess alcohol, especially beer and spirits
- avoiding dehydration by drinking plenty of water.
Losing weight sensibly and gradually, if you need to, is the most effective dietary treatment for gout because it can greatly reduce the urate levels in your body. The larger someone’s body is, the more urate is produced.
Weight loss should be gradual and combined with daily exercise. Extreme weight loss or starvation diets increase cell breakdown in your body, which can raise urate levels.
The best way to lose weight is to have a low-fat, balanced and nutritious diet and to exercise regularly, preferably daily.
If you are new to exercise or haven’t exercised for a while, it might be a good idea to talk to your doctor before exercising. A sensible and sustainable approach is to start off an exercise regime with fairly short, but frequent workout sessions, and then to gradually build up the length and intensity of your exercise sessions. Aerobic exercise in which you get out of breath is particularly good for burning calories.
If you regularly burn off more calories than you consume on a daily basis you will lose weight. Determination and motivation are key factors in losing weight.
It helps to find a sport or exercise you enjoy which you will keep doing. Some people find that joining a leisure centre or sports club can help as meeting new people can be fun and motivational.
Lifestyle choices are not the main reason why most people get gout. However, someone who has a healthy lifestyle and also takes prescribed medication will give themselves the best chance of lowering urate levels and this will reduce the likelihood of having attacks of gout.
We don’t recommend Atkins-type weight loss diets for people who are prone to gout. These diets include a lot of meat and are therefore high in animal proteins, which are high in purines and which break down to produce urate.