Gout is a disease that results from an overload of uric acid in the body.
This overload of uric acid leads to the formation of tiny crystals of urate that deposit in tissues of the body, especially the joints. When crystals form in the joints, it causes recurring attacks of joint inflammation (arthritis). Gout is considered a chronic and progressive disease.
Chronic gout can also lead to deposits of hard lumps of uric acid in the tissues, particularly in and around the joints and may cause joint destruction, decreased kidney function, andkidney stones (nephrolithiasis).
Gout has the unique distinction of being one of the most frequently recorded medical illnesses throughout history. It is often related to an inherited abnormality in the body's ability to process uric acid. Uric acid is a breakdown product of purines that are part of many foods we eat.
An abnormality in handling uric acid can cause attacks of painful arthritis (gout attack), kidney stones, and blockage of the kidney-filtering tubules with uric acid crystals, leading tokidney failure. On the other hand, some people may only develop elevated blood uric acid levels (hyperuricemia) without having manifestations of gout, such as arthritis or kidney problems.
The state of elevated levels of uric acid in the blood without symptoms is referred to as asymptomatic hyperuricemia. Asymptomatic hyperuricemia is considered a precursor state to the development of gout. The term gout refers the disease that is caused by an overload of uric acid in the body, resulting in painful arthritic attacks and deposits of lumps of uric acid crystals in body tissues.
Gouty arthritis is typically an extremely painful attack with a rapid onset of joint inflammation. The joint inflammation is precipitated by deposits of uric acid crystals in the joint fluid (synovial fluid) and joint lining (synovial lining).
Intense joint inflammation occurs as the immune system reacts, causing white blood cells to engulf the uric acid crystals and chemical messengers of inflammation to be released, leading to pain, heat, and redness of the joint tissues. As gout progresses, the attacks of gouty arthritis typically occur more frequently and often in additional joints.
Who is affected by gout?
Approximately 5 million people in the United States suffer from gout. (Did you know that none other than Benjamin Franklin had terribly painful gouty arthritis?) Gout is nine times more common in men than in women. It predominantly attacks males after puberty, with a peak age of 75. In women, gout attacks usually occur after menopause.
While an elevated blood level of uric acid may indicate an increased risk of gout, the relationship between hyperuricemia and gout is unclear. Many patients with hyperuricemia do not develop gout (asymptomatic hyperuricemia), while some patients with repeated gout attacks have normal or low blood uric acid levels.
In fact, the blood level of uric acid often lowers during an acute attack of gout. Among the male population in the United States, approximately 10% have hyperuricemia. However, only a small portion of those with hyperuricemia will actually develop gout.
The small joint at the base of the big toe is the most common site of an acute gout attack of arthritis. An acute attack of gouty arthritis at the base of the big toe is medically referred to as podagra. Other joints that are commonly affected include the ankles, knees, wrists, fingers, and elbows. Acute gout attacks are characterized by a rapid onset of pain in the affected joint followed by warmth, swelling, reddish discoloration, and marked tenderness.
Tenderness can be intense so that even a blanket touching the skin over the affected joint can be unbearable. Patients can develop fever with the acute gout attacks. These painful attacks usually subside in hours to days, with or without medication. In rare instances, an attack can last for weeks. Most patients with gout will experience repeated attacks of arthritis over the years.
Uric acid crystals can deposit in tiny fluid-filled sacs (bursae) around the joints. These urate crystals can incite inflammation in the bursae, leading to pain and swelling around the joints (a condition called bursitis). In rare instances, gout leads to a more chronic type of joint inflammation that mimics rheumatoid arthritis.
In chronic (tophaceous) gout, nodular masses of uric acid crystals (tophi) deposit in different soft-tissue areas of the body. Even though they are most commonly found as hard nodules around the fingers, at the tips of the elbows, in the ears, and around the big toe, tophi nodules can appear anywhere in the body.
They have been reported in unexpected areas such as in the vocal cords or (rarely) even around the spinal cord. When tophi appear in the tissues, the gout condition is felt to represent a substantial overload of uric acid within the body.
In addition to an inherited abnormality in handling uric acid, other risk factors for developing gout include obesity, excessiveweight gain (especially in youth), moderate to heavy alcohol intake, high blood pressure, and abnormal kidney function.
Certain drugs, such as thiazide diuretics (hydrochlorothiazide [Dyazide]), low-doseaspirin, niacin, cyclosporine, tuberculosismedications (pyrazinamide and ethambutol), and others can also cause elevated uric acid levels in the blood and lead to gout. Furthermore, certain diseases lead to excessive production of uric acid in the body. Examples of these diseases includeleukemias, lymphomas, and hemoglobindisorders.
Interestingly, one study demonstrated an increased prevalence of abnormally low thyroid hormone levels (hypothyroidism) in patients with gout.
In patients at risk of developing gout, certain conditions can precipitate acute attacks of gout. These conditions include dehydration, injury to the joint, fever, excessive eating, heavy alcohol intake, and recent surgery. Gout attacks triggered by recent surgery are probably related to changes in the body-fluid balance as patients temporarily discontinue normal oral fluid intake in preparation for and after their operation.
There are two key concepts essential to treating gout. First, it is critical to stop the acute inflammation of joints affected by gouty arthritis. Second, it is important to address the long-term management of the disease in order to prevent future gouty arthritis attacks and shrink gouty tophi crystal deposits in the tissues.
The treatment of an acute attack of gouty arthritis involves measures and medications that reduce inflammation. Preventing future acute gout attacks is equally as important as treating the acute arthritis.
Prevention of acute gout involves maintaining adequate fluid intake, weight reduction, dietary changes, reduction in alcohol consumption, and medications to lower the uric acid level in the blood (reduce hyperuricemia).
Maintaining adequate fluid intake helps prevent acute gout attacks. Adequate fluid intake also decreases the risk of kidney stone formation in patients with gout. Alcohol is known to have diuretic effects that can contribute to dehydration and precipitate acute gout attacks. Alcohol can also affect uric acid metabolism to cause hyperuricemia.
Therefore, alcohol has two major effects that worsen gout by impeding (slowing down) the excretion of uric acid from the kidneys as well as by causing dehydration, both of which contribute to the precipitation of uric acid crystals in the joints.
Dietary changes can help reduce uric acid levels in the blood. Since purine chemicals are converted by the body into uric acid, purine-rich foods are avoided. Examples of foods rich in purines include shellfish and organ meats such as liver, brains, kidneys, and sweetbreads. Researchers have reported, in general, that meat or seafood consumption increases the risk of gout attacks, while dairy food consumption seemed to reduce the risk.
Protein intake or purine-rich vegetable consumption was not associated with an increased risk of gout. Total alcohol intake was strongly associated with an increased risk of gout (beer and liquor were particularly strong factors). Fructose from the corn syrup in soft drinks also increases the risk of gout.
Weight reduction can be helpful in lowering the risk of recurrent attacks of gout. This is best accomplished by reducing dietary fat and calorie intake, combined with a regular aerobic exercise program.