Kidney Stones - Causes

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Family History

A family history of kidney stones increases one's risk for the condition. Researchers are looking into markers or other factors that might predict the onset of stones in relatives, although none has yet been clearly identified. One report found that among the siblings of patients with calcium stones, sisters with higher urinary calcium levels and more acidic urine were more likely to develop stones. Brothers with high urinary calcium, low urinary potassium, and older age were more likely to have the problem. A family history of gout may also predispose a person to stones.

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%).

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. Studies have reported the highest occurrence of kidney stones in the southern region of the United States and the lowest in the west. One study suggested that the higher risk may be due to a higher rate of hypertension in the southern states 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. However, several studies have shown that increasing dietary calcium and restricting salt, animal protein, and foods rich in oxalate can help prevent calcium oxalate stones from returning.

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 in response to stress. Vasopressin also increases the concentration of urine.