Gouty arthritis, also known as gout, is a condition caused by the deposition of needle-like crystals of uric acid (monosodium urate). These crystals accumulate in joint fluid and tissues, causing inflammation, swelling, and severe pain. The most frequently affected joint is the big toe, but gout can also occur in the hands, elbows, wrists, knees, ankles, and feet.
Attacks of gout may occur sporadically and last for several days. During these attacks, uric acid deposits may build up in cartilage, tendons, and soft tissues. They may also form lumps called tophi under the skin. Crystals that accumulate in the kidneys can lead to kidney stones and kidney damage. Most gout episodes are acute and last a few days, but the severity and frequency of attacks can increase, with some people developing a chronic form of gout.
Uric acid is an end product of the breakdown of purines, compounds found in all body tissues and in many foods, such as liver, dried beans, asparagus, mushrooms, and anchovies. Uric acid is normally carried through the blood and eliminated in the urine. If production of uric acid increases, a person eats a large quantity of foods high in purines, or if the kidneys are unable to adequately eliminate uric acid, then concentrations in the blood can rise (called hyperuricemia). When the crystals accumulate in the joints, they can cause the pain associated with gout.
Gout develops more frequently in men than women. It is more common in adults, usually occurring in men over the age of 30 and in women after menopause. People with a family history of gout or who are obese or who have hypertension, type 2 diabetes, hyperlipidemia, cardiovascular disease, or kidney disease are at increased risk of developing gout. Gout has also been associated with metabolic syndrome, a term often used to describe a cluster of these symptoms. Drugs such as cyclosporine, thiazide diuretics (used to treat hypertension), and salicylates (aspirin) can interfere with uric acid excretion as can excessive consumption of alcohol.
Gout must be distinguished from conditions that can cause similar symptoms, such as calcium pyrophosphate deposition (CPPD, formerly called pseudogout), a condition caused by the deposit of calcium pyrophosphate crystals, septic arthritis (caused by an infection in a joint), and rheumatoid arthritis (an autoimmune arthritis). The treatment of these conditions is different than those used in the management of gout.