Gout is a form of arthritis that causes inflammation and severe pain in joints such as the knee, foot, ankle or wrist and particularly in the base of the big toe.
Gout is a reaction that occurs when a chemical called uric acid forms sodium urate crystals in the joints. The crystals can also form in ligaments and tendons around the joints, as well as underneath the skin. Gout usually only affects one joint in the body, but may sometimes involve more than one joint, in which case the condition is referred to as polyarticular gout. This is more likely to develop in older individuals and particularly in women.
This common disease affects about one in 15 men and one in 35 women, usually between the ages of 30 and 60 years. Among men, the condition tends to occur after puberty, whereas among women, it is unlikely to develop before menopause is reached. In about one in ten cases, those affected by gout have a family history of the condition.
For many people who develop gout, the condition is painful and debilitating enough to restrict simple, day-to-day activities and can lead to people taking time off work.
One of the main symptoms of gout is acute pain in the affected joint. This often occurs in the joint of the big toe, although any joint in the body may be affected. Other symptoms include redness, warmth and swelling in the joint area.
The symptoms usually develop rapidly and pain becomes the most intense within just 6 to 24 hours of onset. This is referred to as a “gout attack.” The symptoms can last for between three and ten days, after which point the joint starts to feel normal again and pain subsides. It is possible for a person to experience just one gout attack, which resolves without requiring treatment, but most people who develop the condition are likely to experience further attacks at a later stage.
Gout attacks often occur in the middle of the night or early hours of the morning, with a person waking up to a sensation in the big toe that is so swollen and tender that even a bed sheet resting on it may be unbearable. The skin can also appear red and shiny and even peel in cases of severe inflammation. Sometimes, fatigue, loss of appetite and a mild fever accompany an acute gout attack.
Causes and pathology
Uric acid is formed in the body as a breakdown product of substances called purines. Purines are found in foods such as red meat, shellfish and offal, as well as some kinds of alcohol including beer and stout. One of the most common factors associated with the development of gout is an excess alcohol intake, particularly of beer. The purines found in foods generally account for up to 10% of the total purines found in the body.
As redundant cells are broken down or during the digestion of food, purines are converted into uric acid, which is transported in the bloodstream as a salt called urate. Urate is usually excreted by the kidneys. However, if uric acid is produced in excess or if the urate excretion process is compromised, uric acid can accumulate to an abnormal level in the blood. Over several years, hard and needle-shaped sodium urate crystals then form.
The urate crystals that form may irritate the soft lining of the joint called the synovium, causing inflammation and joint pain. In cases of long-term or chronic gout, some of the crystals may also clump together to form lumps in the soft flesh of the feet, elbows, hands or earlobes. These deposits are referred to as “tophi”. These tophi can eventually cause irreversible damage to the joint cartilage and adjacent bone, leading to pain and stiffness whenever the joint is used. If the blood urate level is high enough, similar deposits may start to build up in the kidneys, eventually leading to painful kidney stones.
Usually, the cause of a high blood urate level is inadequate excretion of urate via the urine, but other causes include a diet high in uric acid, stress, crash dieting, dehydration, injury, persistent illness and the use of some drugs such as diuretics or aspirin. Less commonly, gout is caused by a genetic tendency to produce too much uric acid. Not everybody who has a high blood urate level develops gout, but this is more likely to occur if a person is overweight. Following a healthy diet and maintaining a normal weight can reduce the likelihood of gout developing.
Sometimes gout is associated with the presence of other health conditions such as hypertension, diabetes, angina, stroke, psoriasis, poor circulation or kidney disease. The presence of gout may therefore be a warning sign of another underlying condition the patient is unaware of.
A simple blood test can be performed to determine whether a person has a high blood uric acid level, but this alone is insufficient to diagnose a gout attack. A diagnosis is confirmed using a more specific test that analyses fluid from the joint concerned. The fluid is aspirated and then assessed using microscopy to look for any urate crystals that have formed.
Gout is one of the few forms of arthritis that can be treated to avoid further damage to joints. Mild cases of gout can sometimes be prevented through dietary changes alone, but recurring gout may require a long-term treatment programme to stop the attacks and any associated complications such as bone, cartilage or kidney damage.
The management of gout involves a three-stage approach: the gout attack is treated, dietary and lifestyle changes are made to reduce the likelihood of further attack and the uric acid level is reduced to prevent recurrence.
To reduce inflammation and pain, a doctor may prescribe a non-steroidal anti-inflammatory drugs (NSAID), colchicine or corticosteroids. Sufferers can reduce the likelihood of another attack by making any recommended lifestyle changes such as losing weight, reducing alcohol consumption, and decreasing their intake of purine-rich foods such as seafood, offal or red meat. People who find the gout attacks still occur are prescribed long-term medication to ensure their blood urate level is lowered.