Kidney Stones - Risk Factors

Ethnicity

According to a 2003 study, of American ethnic groups, Caucasians have the highest incidence of kidney stones (5.9%) followed by Mexican Americans (2.6%). African Americans have the lowest risk (1.7%).

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Geographic Differences

Dietary factors, minerals in local water, or both may contribute to geographic differences that have been observed in the prevalence of kidney stones. For example, studies report the highest occurrence of kidney stones in the southern region of the US and the lowest in the West.One study suggested that the higher risk may be due to a higher rate of hypertension in the South and certain dietary habits, particularly lower intake of magnesium and low use of calcium supplements. Higher rates of kidney stones have been reported in areas of Australia where magnesium levels in drinking water are low. Hard water tends to have higher amounts of protective calcium and magnesium, although evidence suggests that the hardness or softness of water does not significantly affect risk.

Life Style Factors

Specific Foods. In general, certain foods increase the risk for stones only in people who have genetic or medical susceptibility. People whose diets are high in animal protein and low in fiber and fluids may be at higher risk for stones. A number of foods contain oxalic acid, but there is no proof that such foods make any major contribution to calcium oxalate stones in people without other risk factors. Dietary calcium appears to be protective.

Stress. One study reported that people who had a major, stressful life experience were more likely to develop stones than those who had not. Some experts speculate that this increased risk may be due to a hormone called vasopressin, which is released during stress. Among its other functions, vasopressin increases the concentration of urine.

Sleep Position. Sleeping in the same position consistently may influence risk. A 2001 study reported that in people who had a history of kidney stones, recurrences tended to occur on the same side that people favored. An earlier study suggested that people who had kidney stones were more apt to sleep on their stomachs. Movement during sleep did not appear to affect the risk.

Being Bedridden. Any medical or physical condition that results in a patient being immobilized or bedridden increases blood levels of calcium from bone breakdown, thereby posing a risk for stone formation.

Medical Conditions

Gout. A 2002 study reported that the prevalence of kidney stones in patients with gout was 13%.The study strongly suggests that the two disorders may share a common mechanism.