Gout is a type of arthritis characterized by sudden, severe attacks of joint pain with tenderness, redness, warmth, and swelling in the affected area. It usually attacks only one joint at a time. It most often strikes the joint of the big toe, also known as podagra, but other joints can also be involved.
Gout is typically a condition that affects people in their middle age and older, and is unusual in people under the age of 30. It is twice as common in men as in premenopausal women. Women develop gout equally as often as men after menopause (estrogens, which are at higher levels before menopause, appear to play a protective role).
Certain medications and diseases can bring on gout in anyone of any age or gender. A first gout attack most commonly occurs in the mid-40s. It is found universally and has been described as far back as the time of Hippocrates, 2,500 years ago. It affects about 1% of the population.
The pain and swelling of a gout attack are caused by uric acid crystals building up in the joint and leading to inflammation. The body normally forms uric acid when breaking down protein. The uric acid usually stays dissolved in the blood and ends up being flushed out by the kidneys.
If there's too much uric acid in the blood, called hyperuricemia, or if the kidneys can't get rid of it quickly enough, the blood level of dissolved uric acid rises beyond what the blood can hold. As a result, crystals form and may be deposited in joints or various storage areas. Excess uric acid in the urine also crystallizes and can deposit in the kidneys and act as the seed to form calcium kidney stones.
In severe cases, the uric acid deposits are so large that they can extend out to the skin and beyond. These large deposits around the joints and cartilage (such as the outer ear) are called tophi. Gout can also cause severe bursitis.
Most people with gout have elevated uric acid levels for a long time, often up to 20 years, before the first gout attack. Uric acid levels begin to rise after puberty. They are especially increased in people who have excess visceral fat (fat that is inside the body and surrounding the intestines, liver, and heart), who eat unhealthy diets, and who often have high blood pressure, high cholesterol, and high blood sugar.
Certain high-protein foods can make the body produce too much uric acid, triggering gout. Beverages such as tea, coffee, cocoa, and especially alcohol in any form lead to extra water loss from the body, which can cause an attack. Certain medications can hamper the kidneys' ability to clear out uric acid, including low-dose aspirin* and diuretics ("water pills") commonly given to control high blood pressure. Finally, sudden changes in diet and weight gain or loss can also lead to gout.
Gout occurs often in joints that have previously been injured. 95% of people with gout have had an attack in a large toe at some point, since almost everyone has injured that toe repeatedly over their lives.