Gout ( GOWT), also called rheumatic gout, is a form of inflammatory arthritis characterized by recurrent attacks of pain in a red, tender, hot, and swollen joint, caused by the deposition of needle-shaped crystals of the monosodium salt of uric acid. Pain typically comes on rapidly, reaching maximal intensity in less than 12 hours. In about half of cases, the joint at the base of the big toe is affected (podagra). It may also result in tophi, kidney stones, or kidney damage. Gout is due to persistently elevated levels of uric acid (urate) in the blood (hyperuricemia). This occurs from a combination of diet, other health problems, and genetic factors. At high levels, uric acid crystallizes and the crystals deposit in joints, tendons, and surrounding tissues, resulting in an attack of gout. Gout occurs more commonly in those who regularly drink beer or sugar-sweetened beverages, eat foods that are high in purines such as liver, shellfish, or anchovies, or are overweight. Diagnosis of gout may be confirmed by the presence of crystals in the joint fluid or in a deposit outside the joint. Blood uric acid levels may be normal during an attack. Treatment with nonsteroidal anti-inflammatory drugs (NSAIDs), glucocorticoids, or colchicine improves symptoms. Once the acute attack subsides, levels of uric acid may be lowered via lifestyle changes and in those with frequent attacks, allopurinol or probenecid provides long-term prevention. Taking vitamin C and having a diet high in low-fat dairy products may be preventive. Gout affects about 1–2% of adults in the developed world at some point in their lives. It has become more common in recent decades. This is believed to be due to increasing risk factors in the population, such as metabolic syndrome, longer life expectancy, and changes in diet. Older males are most commonly affected. Gout was historically known as "the disease of kings" or "rich man's disease" for its relationship to a rich diet and obesity. It has been recognized at least since the time of the ancient Egyptians.
Signs and symptoms
Gout can present in several ways, although the most common is a recurrent attack of acute inflammatory arthritis (a red, tender, hot, swollen joint). The metatarsophalangeal joint at the base of the big toe is affected most often, accounting for half of cases. It can also involve midfoot structures, including the cuneiform bones. Other joints, such as the heels, knees, wrists, and fingers, may also be affected. Joint pain usually begins during the night and peaks within 24 hours of onset. This is mainly due to lower body temperature. Other symptoms may rarely occur along with the joint pain, including fatigue and high fever. Long-standing elevated levels of uric acid (hyperuricemia) may result in other symptoms, including hard, painless deposits of uric acid crystals called tophi. Extensive tophi may lead to chronic arthritis due to bone erosion. Elevated levels of uric acid may also lead to crystals precipitating in the kidneys, resulting in kidney stone formation and subsequent acute uric acid nephropathy.
Cause
The crystallization of uric acid, often related to relatively high levels in the blood, is the underlying cause of gout. This can occur because of diet, genetic predisposition, or underexcretion of urate, the salts of uric acid. Underexcretion of uric acid by the kidney is the primary cause of hyperuricemia in about 90% of cases, while overproduction is the cause in less than 10%. About 10% of people with hyperuricemia develop gout at some point in their lifetimes. The risk, however, varies depending on the degree of hyperuricemia. When levels are between 415 and 530 μmol/L (7 and 8.9 mg/dL), the risk is 0.5% per year, while in those with a level greater than 535 μmol/L (9 mg/dL), the risk is 4.5% per year.
Lifestyle Dietary causes account for about 12% of gout. In particular the consumption of alcohol, sugar-sweetened beverages, as well as meat and seafood contribute to gout. The dietary mechanisms and nutritional basis involved in gout provide evidence for strategies of prevention and improvement of gout, and dietary modifications based on effective regulatory mechanisms may be a promising strategy to reduce the high prevalence of gout. Among foods richest in purines yielding high amounts of uric acid are dried anchovies, shrimp, organ meat, dried mushrooms, seaweed, and beer yeast. Chicken and potatoes also appear related. Other triggers include physical trauma and surgery. Studies in the early 2000s found that other dietary factors are not relevant. Specifically, a diet with moderate purine-rich vegetables (e.g., beans, peas, lentils, and spinach) is not associated with gout. Neither is total dietary protein. Alcohol consumption is strongly associated with increased risk, with wine presenting somewhat less of a risk than beer or spirits. Eating skim milk powder enriched with glycomacropeptide (GMP) and G600 milk fat extract may reduce pain but may result in diarrhea and nausea. Physical fitness, healthy weight, low-fat dairy products, and to a lesser extent, coffee and taking vitamin C, appear to decrease the risk of gout; however, taking vitamin C supplements does not appear to have a significant effect in people who already have established gout. Peanuts, brown bread, and fruit also appear protective. This is believed to be partly due to their effect in reducing insulin resistance. Other than dietary and lifestyle choices, the recurrence of gout attacks is also linked to the weather. High ambient temperature and low relative humidity may increase the risk of a gout attack.
Genetics Gout is partly genetic, contributing to about 60% of variability in uric acid level. The SLC2A9, SLC22A12, and ABCG2 genes are commonly associated with gout and variations in them can approximately double the risk. Loss-of-function mutations in SLC2A9 and SLC22A12 causes low blood uric acid levels by reducing urate absorption and unopposed urate secretion. The rare genetic disorders familial juvenile hyperuricemic nephropathy, medullary cystic kidney disease, phosphoribosylpyrophosphate synthetase superactivity and hypoxanthine-guanine phosphoribosyltransferase deficiency as seen in Lesch–Nyhan syndrome, are complicated by gout.
… excerpt ends here. Continue reading the full article.
