Gout

Gout is a type of arthritis, which is a group of related disorders caused by episodes of abnormal inflammation in the joints. People with gout have high levels of a substance called urate in the blood (hyperuricemia). Gout develops when hyperuricemia leads to the formation of urate crystals in joints, triggering an inflammatory response from the immune system.

In people with gout, the first episode of inflammation (called a flare) usually affects the big toe or other joints in the foot or ankle. If urate levels remain high, flares can recur, affecting additional joints throughout the body. The time between flares varies among affected individuals; however, most people who experience multiple flares have their second one within a year of their first.

Flares usually begin at night and can last several days. It is unclear what causes a flare to stop; the body likely turns off the inflammation response after a certain period of time. During a flare, individuals can experience throbbing or burning pain, swelling, warmth, redness, and difficulty moving the affected joint. Fevers may occur, after which the skin over the affected joint can begin to peel. Without treatment, people with gout can experience frequent flares and joint pain and damage, which can limit mobility and decrease quality of life.

In about 15 percent of people with gout, urate accumulates in the kidneys and forms kidney stones. As the condition worsens, urate crystals can also be deposited under the skin or in other soft tissue, forming a nodule called a tophus (plural: tophi). These tophi often form in the hands, elbows, or feet. Tophi do not typically cause pain, but they can become inflamed, infected, or ooze fluid. Depending on their location, tophi can interfere with movements such as walking or gripping objects.

Many people with gout also have other health conditions. Most affected individuals have high blood pressure (hypertension), chronic kidney disease, or obesity. Some also have diabetes, heart disease, or a history of stroke. It is unclear whether gout is the cause of a person's increased risk for these conditions, or whether the conditions cause the development of gout, or whether both of these situations occur to influence disease.