Gout

Description

Alternative Names

Risk Factors

Risk factors are attributes or activities associated with a greater-than-normal likelihood of developing a particular disorder. Sometimes a causal connection between the attribute or activity and the disorder can be established, but at other times there is simply a statistical correlation. The risk factors for gout, of which there are several, are identical to those for hyperuricemia.

Prevalence

Gout is the second most common inflammatory arthritic condition in older adults. Based on self-reports, gout is estimated to affect about 2.1 million Americans (1.56 million men and 550,000 women). Some experts believe, however, that this may be an overestimate. The prevalence of gout has been rising in recent decades, not only in America but in other developed countries, possibly because of dietary and lifestyle changes, greater use of medications that cause hyperuricemia, and aging populations.

Gout is very uncommon in less-developed countries, however, and in 1952 it was said to be unknown in China, Japan, and the tropics.

Age

Middle-Aged Adults. Gout usually occurs in middle-aged men, peaking in the mid-40s. It is most often associated in this age group with obesity, high blood pressure, unhealthy cholesterol levels, and heavy alcohol use.

Elderly. Gout can also first develop in older people, when it occurs equally in men and women. In this group, gout is most often associated with kidney problems and the use of diuretics. It is less often associated with alcohol use.

Children. Among children, the levels of uric acid in both girls and boys are low, averaging 3 to 4 mg/dL. Except for rare inherited genetic disorders that cause hyperuricemia, gout in children is almost unheard of.

Gender

Men. Men are significantly at higher risk for gout. In males, uric acid levels rise substantially at puberty, with the result that the level exceeds 7 mg/dL (considered to indicate hyperuricemia) in about 5% to 8% of American men. Gout typically strikes only after 20 to 40 years of persistent hyperuricemia, however, so men who develop it usually experience their first attack between the ages of 30 and 50 years. In one study that followed male medical students for 28 years, the prevalence of gout was 5.8% in Caucasian men and 10.9% in African American men.

Women. Before menopause, women have a significantly lower risk for gout than men, possibly because of the actions of estrogen. This female hormone appears to facilitate uric acid excretion by the kidneys. (Only about 15% of female gout cases occur before menopause.) After menopause the risk increases in women so that after age 60 the incidence is equal in men and women, and after 80, gout occurs actually more often in women.

Family History

A fairly substantial proportion of patients with gout (10% to 20%) has a family history of gout. According to a 2001 Taiwan study, patients with possible inherited conditions were more likely to have an earlier onset (about 41 years) compared to those whose gout is due to other factors (48 years). They were also more likely to have family histories of obesity, type 2 diabetes, and kidney insufficiencies.

Other Risk Factors

Obesity. Researchers report a clear link between body weight and uric acid levels. In one Japanese study, overweight people had between two and over three times the incidence of hyperuricemia as those of normal or low weights. Obesity may be an especially important risk factor for gout in men. Children who are obese may have a higher risk for gout in adulthood.

Hypertension and Diuretics. The use of diuretics, which are agents used to treat high blood pressure, is highly associated with gout. Hypertension (high blood pressure), itself, is found in 25% to 50% of patients with gout, but whether it causes hyperuricemia is uncertain.

Consumption of purine-rich foods. A 2004 study showed that higher consumption of purine-rich foods such as meat and seafood was associated with a significantly increased risk of gout. However, purine-rich vegetables did not increase gout risk. Interestingly, the same study showed that consumption of dairy products had a protective effect against gout.

Alcohol Use. Alcohol use is highly associated with gout in younger adults. Binge drinking particularly increases uric acid levels. It appears to play less of role among elderly patients, especially among women with gout. A major 2004 study showed that among alcoholic beverages, beer is the most strongly linked with gout, followed by spirits. However, moderate wine consumption does not appear to increase the risk of developing gout.

Thyroid Dysfunction. Some studies have reported a higher prevalence of gout in people with hypothyroidism (low levels of thyroid hormone). Hypothyroidism may even trigger gout. There is also some evidence to suggest that hyperthyroidism (high levels of thyroid hormone) can increase uric acid levels, although not to the degree that low thyroid hormones levels do.