Gout: Causes, symptoms and treatment
What is gout?
Gout is a common form of arthritis where crystals form in and around joints causing pain, swelling and redness.
Gout often affects the big toe, but can also affect other joints including knees, ankles, elbows, thumbs or fingers.
Gout affects around 1 in 45 people in the UK, and is more common in men than it is in women. When women develop gout, it is usually after the menopause.
Image: Dr P Marazzi/Photo Researchers, Inc.
Attacks of gout can be unexpected and excruciatingly painful. With prompt treatment, the pain and inflammation usually disappear after a few days, but they may recur at any time.
Crystal deposits in the joints
Gout is the body's reaction to irritating crystal deposits in the joints. Here, uric acid crystals have affected the base of the joint of the big toe.
X-ray image: eMedicine.com, 2008
The pain can be intense, but treatment usually works very well.
In mild cases attacks may be prevented by diet alone, but recurring attacks of gout may require long-term medication to prevent recurrent attacks and damage to bones and cartilage and deterioration of the kidneys.
Chronic gout sufferers may feel tiny, hard lumps accumulating over time in the soft flesh of areas such as the hands, elbows, feet or earlobes. These deposits, called tophi, are concentrations of uric acid crystals and can cause pain and stiffness over time. If similar deposits form in the kidneys, they can lead to painful and potentially dangerous kidney stones.
What causes gout?
An excess of uric acid in the blood brings on gout. Uric acid comes from two places - produced by the body and from the diet. Any extra uric acid usually filters through the kidneys and gets passed in the urine. If the body produces too much uric acid, or fails to excrete it, crystals form and become concentrated in the joints and tendons. This causes swelling, pressure and severe pain.
Nobody knows exactly why gout develops. One of the most common factors that increase the chance of developing gout is excess consumption of alcohol, particularly beer because it is high in purines. Gout used to be known as “the disease of kings” since it was mainly seen in wealthy men who drank and ate too much. Now we know it can occur in anyone and can also be associated with an injury or surgical procedure, hospitalisation or periods of stress, or it can be a consequence of certain medication such as diuretics. Gout may also occur in the presence of some tumours or cancers. Research shows a relationship between gout and kidney disorders, enzyme deficiencies and lead poisoning. Gout may also accompany psoriasis or anaemia and is common in patients with transplanted organs. Susceptibility to gout can be inherited and is often associated with other common conditions such as high blood pressure, diabetes and obesity. Repeat attacks are common if the body's uric acid level is not kept under control.
Pseudogout is a similar but generally less painful condition caused by calcium pyrophosphate crystals in the joints. While it can affect the large toe, it is more commonly seen in larger joints such as the knee, wrist or ankle. More common after the age of 60 in both sexes, pseudogout is treated with anti-inflammatory agents or, in severe cases, surgery followed by cortisone injections.