Gout is a form of arthritis which is caused by the development of crystals, made of a chemical called uric acid, in the joints of the body. Unlike other types of arthritis, the symptoms of gout can appear suddenly, even while the joint is at rest. Gout can affect the knees as well as other joints in the body and can be treated using pain relievers and medications which prevent future attacks.
Symptoms
Although gout typically first causes pain in the big toe, it can also affect the knee, the Mayo Clinic explains. Pain caused by gout is often very severe and comes on suddenly, especially at night. Even once the initial burst of pain in the knee has subsided, patients can feel pain and discomfort that lingers for weeks after the initial attack.
Gout and Uric Acid
Gout is caused by the formation of small crystals made of uric acid, according to the National Institute of Arthritis and Musculoskeletal Diseases (NIAMS). Uric acid is the breakdown product of a chemical called purines, which are found throughout the body and in many foods. Normally uric acid is dissolved in the blood and is eliminated by the kidneys. Patients with an excess of uric acid, however, can develop crystals in their knees and other joints, leading to inflammation and pain.
Risk Factors
Age and gender are two major risk factors for gout; it is most common in older men. Patients who drink large amounts of alcohol on a regular basis (more than two drinks a day for men, one a day for women) are also more likely to have gout. High blood pressure, diabetes, arteriosclerosis and high cholesterol levels can also put a patient at risk for developing gout. Finally, patients with a family history of gout are at a higher risk than the general population.
Diagnosis
Gout can be difficult to diagnose, the American College of Rheumatology explains, because it can mimic other kinds of arthritis. Patients who have gout in their knees also often will have other affected joints. Gout may be suspected for patients who have sudden episodes of knee pain, especially if they occur at night. A definitive diagnosis usually requires the physician to take a sample of the fluid from the knee (or other joints) and then look at the sample under a microscope to see if there are uric acid crystals.
Treatment
Treatment for gout aims at both relieving the pain and preventing future attacks. Pain relief can come from taking non-steroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen or naproxen. Colchicine, the Mayo Clinic explains, can also be used to treat gout pain. Severe attacks can be treated with corticosteroids, which will reduce the inflammation. Xanthine oxidase inhibitors (such as allopurinol) can be used to prevent future attacks, as can probenecid.
