When pediatric urologist Barry Duel began practicing 11 years ago, it was rare to see a healthy child with kidney stones. These days, he sees two to three new children with stones a month.
Craig Langman, head of the department of kidney diseases at Children's Memorial Hospital in Chicago, has 800 pediatric patients in his files with kidney stones. More than half of them are from the past five years. Kidney stones are small, hard masses of mineral and acid salts that separate from the urine and solidify in the kidney. Most commonly, they are made of calcium oxalate or calcium phosphate, although other types exist.
Urine typically contains chemicals such as citrate, magnesium and pyrophosphate that prevent these crystals from forming. Stone patients can have low levels of these chemicals, causing stone formation. Stones can also form when a person is dehydrated, lacking the fluid to flush the minerals that form stones.
Root causes
Most urologists believe that the rise in rates is linked to the increase in childhood obesity and poor diets.
* Obesity. High levels of glucose, triglycerides, cholesterol and insulin affect acidity of the urine. Studies at UT Southwestern Medical Center in Dallas have shown that people with metabolic syndrome -- characterized by obesity, high blood pressure, diabetes and high cholesterol -- are at an increased risk for kidney stones. High levels of insulin, in particular, correlate with higher urine acid levels, which can cause uric acid stones.
* Too much dietary sodium. Most stones are made of calcium, and an abundance of sodium causes the body to release more calcium into the urine. Physicians worry that sodium intake in children is on the rise because they are drinking more sodas, eating more often at restaurants and noshing on more convenience foods.
* Lack of dietary calcium. This may seem counterintuitive because stones are made of calcium, but if children have a low calcium intake, it can cause their gastrointestinal tract to overabsorb the chemical oxalate, a component of stones.
Several measures can help decrease the likelihood of a stone recurring again. Drinking lots of fluids (mainly water) keeps chemicals such as calcium oxalate from reaching high concentrations in the urine. Drinking lemonade, which contains citrate, helps prevent calcium from crystallizing in the urine. Physicians also recommend reducing salt intake and ensuring children are getting their recommended calcium, which is 800 milligrams for children ages 4 to 8 and 1,300 milligrams for ages 9 to 18.
Medical treatments include the use of diuretics; Langman says he has had success prescribing Thiazide, a diuretic that blocks the kidney's excretion of calcium.
More information on kidney stones can be found on the National Kidney Foundation's website at www.kidney.org.
Source: LA Times
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