Gout is a type of arthritis that involves sudden, severe attacks of joint pain. It is caused by deposits of needle-like crystals in joints and surrounding tissues Figure 01. In the past, gout was thought of as a disease of the wealthy because it seemed to result from eating rich food and drinking alcohol. In fact, anyone can develop gout; diet is not necessarily a major factor.
Gout results from an excess of uric acid (a substance formed from the breakdown of cells) in the blood. The excess uric acid forms crystals that build up in the spaces inside the joints, which then become swollen, red, stiff, and painful.
Figure 01. Gout in the big toe (podagra)
The joints most often affected are those of the big toe, the instep, heels, ankles, knees. Fingers, wrists, and elbows may also be affected.
Gout can develop in four stages. In the later stages of gout, hard deposits of crystals called tophi may develop as lumps under the skin around the joints. The crystals may also collect in the kidneys and cause kidney stones.
- Excess uric acid without symptoms. In this stage, the level of uric acid in your blood is high, but you have no symptoms.
- Acute gout. Excess uric acid in the blood causes uric acid crystals to build up in your joints, resulting in swollen joints and attacks of severe pain that last from 3 to 10 days and sometimes longer.
- Interval gout. In this stage, between acute attacks you have no symptoms and your joints work normally.
- Chronic gout. After a number of years, you develop chronic joint pain and may well have tophi. Your joints are permanently damaged and you may be at risk for kidney stones. With proper treatment, most people do not progress to this stage.
Pseudogout is a disorder that involves sudden attacks of joint pain, but its cause is different from that of gout. Pseudogout also involves crystal deposits in the joints, but its cause is unknown. The crystals of pseudogout are composed of calcium pyrophosphate as opposed to the uric acid crystals of gout. If you have pseudogout, attacks of pain may occur in the larger joints, such as the wrists and knees. These attacks are less painful than those of gout. Between attacks you may have no pain, or you may experience long-term pain and stiffness in the arm and leg joints. Some people with pseudogout have no pain at all, even though their joints show large crystal deposits. About 5% of people with gout also have pseudogout. It is important that your doctor distinguish between gout and pseudogout, because the long-term treatments are different.
In gout, excess uric acid builds up in the blood either because your body produces too much uric acid, or because your kidneys do not excrete enough of it. Excess uric acid is not a disease in itself unless it leads to joint pain or kidney stones. Compounds known as purines, which are found naturally in the body and in some foods, are broken down as a normal body function. A by-product of this metabolism is known as uric acid. Uric acid is dissolved in the blood, passes into the kidneys, and is excreted in the urine. However, if the body produces a large amount of uric acid or the kidneys do not eliminate enough of it, high levels may build up (a condition called hyperuricemia).
Both environmental and genetic factors can contribute to gout Table 01. Certain lifestyle habits, such as drinking a great deal of alcohol, can result in excess production and/or decreased excretion of uric acid. A genetic enzyme defect, leukemia, or cancer chemotherapy, which leads to rapid multiplication and/or destruction of cells, can lead to a buildup of uric acid. Kidney disease and certain drugs may impair the kidneys’ ability to excrete uric acid.
Table 1. Risk Factors for Gout
Behaviors Eating too many foods high in purines, such as liver and other organ meats, dried peas and beans, veal, turkey, and some types of fish, including anchovies, shrimp, mackerel, and scallops. Being overweight. Drinking large amounts of alcohol. Alcohol interferes with excretion of uric acid, and alcoholic beverages contain purines. Exposure to lead in the environment. Medical Conditions An enzyme defect that prevents your body from breaking down purines properly. Diseases that interfere with uric acid excretion, including untreated high blood pressure (hypertension), high levels of fat in the blood (hyperlipidemia), diabetes, kidney disease, narrowing of the arteries (arteriosclerosis), and leukemia. Genetics. Between 6% and 18% of people with gout have a family history of the disorder, which strongly suggests that genetics influences your risk . Surgery and sudden or serious illness or injury can set off an attack of gout. Drugs Diuretics, which are used to treat high blood pressure. These drugs increase the flow of urine but decrease excretion of uric acid. Drugs made from salicylic acid, such as aspirin, when taken in low dose. Niacin, a vitamin also known as nicotinic acid. Cyclosporine, which is used to prevent the body from rejecting transplanted organs.
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