Gout Causes and Diagnosis
Gout occurs in approximately 840 out of every 100,000 people. It is rare in children and young adults.
Adult men, particularly those between the ages of 40 and 50, are more likely to develop gout than women, who rarely develop the disorder before menopause. People who have had an organ transplant are more susceptible to gout.
A number of risk factors are related to the development of hyperuricemia and gout:
- Genetics may play a role in determining a person's risk, since up to 18 percent of people with gout have a family history of the disease.
- Gender and age are related to the risk of developing gout; it is more common in men than in women and more common in adults than in children.
- Being overweight increases the risk of developing hyperuricemia and gout because there is more tissue available for turnover or breakdown, which leads to excess uric acid production.
- Drinking too much alcohol can lead to hyperuricemia because it interferes with the removal of uric acid from the body.
- Eating too many foods rich in purines can cause or aggravate gout in some people.
- An enzyme defect that interferes with the way the body breaks down purines causes gout in a small number of people, many of whom have a family history of gout.
- Exposure to lead in the environment can cause gout.
Some people who take certain medicines or have certain conditions are at risk for having high levels of uric acid in their body fluids. For example, the following types of medicines can lead to hyperuricemia because they reduce the body's ability to remove uric acid:
- Diuretics, which are taken to eliminate excess fluid from the body in conditions like hypertension, edema, and heart disease, and which decrease the amount of uric acid passed in the urine;
- Salicylates, or anti-inflammatory medicines made from salicylic acid, such as aspirin;
- The vitamin niacin, also called nicotinic acid;
- Cyclosporine, a medicine used to suppress the body's immune system (the system that protects the body from infection and disease) and control the body's rejection of transplanted organs; and
- Levodopa, a medicine used to support communication along nerve pathways in the treatment of Parkinson's disease.
Signs and Symptoms of Gout
- Presence of uric acid crystals in joint fluid
- More than one attack of acute arthritis
- Arthritis that develops in 1 day, producing a swollen, red, and warm joint
- Attack of arthritis in only one joint, usually the toe, ankle, or knee
Gout may be difficult for doctors to diagnose because the symptoms may be vague, and they often mimic other conditions. Although most people with gout have hyperuricemia at some time during the course of their disease, it may not be present during an acute attack. In addition, having hyperuricemia alone does not mean that a person will get gout. In fact, most people with hyperuricemia do not develop the disease.
To confirm a diagnosis of gout, a doctor may insert a needle into an inflamed joint and draw a sample of synovial fluid, the substance that lubricates a joint. A laboratory technician places some of the fluid on a slide and looks for monosodium urate crystals under a microscope. Their absence, however, does not completely rule out the diagnosis. The doctor also may find it helpful to examine chalky, sodium urate deposits (tophi) around joints to diagnose gout. Gout attacks may mimic joint infections, and a doctor who suspects a joint infection (rather than gout) may check for the presence of bacteria.