Gout is a type of arthritis that typically attacks one joint at a time.  It causes red, swollen, painful joints.  It is most common at the base of the great toe, but can occur in any joint. Many of the foods we eat contain purines.  Meats such as liver, sardines and herring, sweetbreads, and beer are some of the foods that contain high concentrations of purines.  As the purines are broken down and metabolized, uric acid is produced.  The uric acid is filtered out of the blood in the kidneys and then excreted in urine.  Unfortunately, some people's bodies are not as good at excreting the uric acid or they produce too much uric acid.  This is likely caused by a combination of factors including diet, lifestyle, genetics, medications, and other medical problems. Whatever the cause, as uric acid builds up in the blood, it begins to crystallize.   These sharp urate crystals precipitate and embed themselves in the synovial tissue that surrounds the affected joint.  This triggers an inflammatory reaction that results in pain, redness, and swelling. Gout is diagnosed by obtaining joint fluid from the affected joint and examining it under a microscope using polarized light.  It is not always possible to obtain joint fluid from the inflamed joint.  A blood test can be performed to measure uric acid levels.  Unfortunately, the test is of limited value, as uric acid levels are often normal during a gout flare-up and because not everyone with high levels of uric acid develops gout. Gout must be distinguished from other causes of joint pain, including septic arthritis.  Septic arthritis is a bacterial infection of the joint.  Gout has been called "the great masquerader" because its signs and symptoms are very similar to those of septic arthritis.  If joint fluid can be obtained, a Gram stain can be performed to look for bacteria.  Acute episodes of gout are treated with non-steroidal anti-inflammatory drugs.  Many different NSAIDs have been used to treat gout, including ibuprofen and indomethacin.  Steroids, such as prednisone, are also used for their anti-inflammatory effect.  They can be taken orally or injected into the joint. Once the acute episode of gout has resolved, measures can be taken to prevent or at least limit future episodes.  Lifestyle changes, including avoiding food rich in purines can be helpful.  A medication known as allopurinol can lower uric acid levels, making future episodes less likely.  However, allopurinol should not be given during an acute episode, as this may make things worse.