What is gout?
Gout is a type of inflammatory arthritis caused by small crystals of a chemical called uric acid that form in the joints. The body’s immune system attacks these crystals, causing pain, redness and swelling in the joint and sometimes in the surrounding tissue. Gout has both active and inactive periods. Active periods of gout are known as “attacks” and can vary in severity and length.
High levels of uric acid cause gout but not everyone with high uric acid levels develops gout. Uric acid results when our bodies break down certain chemicals that occur naturally in our cells and in some high-protein food. Uric acid is taken by the blood to the kidneys where it is disposed of in the urine. When the amount of uric acid in the blood is too high (either because the body produces too much uric acid or because the body cannot get rid of the uric acid it produces), small crystals can form in the joints. These crystals can build up under the skin and form hard bumps called tophi. Uric acid crystals can also deposit in the kidneys causing kidney stones.
Gout attacks can happen in any joint but often impact those in the lower limbs such as the knees, ankles and feet. Many people experience their first gout attack in the base of the big toe. Initial attacks usually stop after three to 10 days; however, without treatment, attacks can occur again and can last longer. Most people with gout will have another attack within a year. Over time, these attacks may become more frequent, last longer and impact more joints. Recurring gout attacks can cause permanent joint damage so early diagnosis and treatment are key.
Unlike other forms of arthritis, gout can start sudden but can also stop suddenly.
This information was last updated September 2017, with expert advice from:
Gregory Choy, MD, FRCPC
Rheumatology Division, Sunnybrook Health Sciences Centre, University of Toronto
Paul MacMullan, MB BCh, BAO, CCST, MRCPI
Internal Medicine & Rheumatology; Clinical Associate Professor, University of Calgary
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