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My 15 year old daughter just had surgery for a kidney stone. Her maternal grandfather suffered with these all his life, so we feel it is hereditary. It is unusual for such a young girl to have a kidney stone. She runs cross country and we also feel she has hydrated enough on a daily basis. The doctor told us to reduce her protein intake as her stone was a uric acid stone. What types of things should be cut out of her diet? Do you have recipes that are low protein for a lifestyle change?
There are a number of types of kidney stones and it is not unusual for children to have them. They are the most common type of kidney stone in kids. This is one of the better articles on the web that can help you understand how the stones form: Uric Acid Stones (Medscape).
Diet can also play a role and reducing the amount of proteins that are high in purines is key to avoiding more stones. This is the same sort of diet that those with gout will follow (gout is also caused by high levels of uric acid in the blood stream). (Here are some dietary guidelines for those with gout from the NIH.) This is not all proteins and since your daughter is an athlete it's important that you make sure that she gets enough protein. There's no definitive research on the exact mix of proteins for those with uric acid stones, but we know that for those who have gout, reducing the amount of animal protein and getting more vegetable protein is OK. Here's a list of foods that are high in purines.
A set of guidelines for those with kidney stones was published in Nutrition Reviews in 2006 (Vol. 64, No. 7):
1. Maintain ideal body weight as nearly as possible.
2. Drink enough water to bring the urinary volume up to at least 2 L/d. Drink the water a little at a time, and consume a water load of approximately 500 mL before going to bed. Consume other fluids but not as a substitute for water.
3. Limit salt (sodium chloride) intake to no more than 6 g/d. It is extremely important to be aware of hidden sources of salt.
4. Limit protein intake deriving from meat, fish, and poultry to about 20 g/d.
5. Consume milk, yogurt, and cheese in amounts corresponding to a calcium intake of about 1200 mg/d (30 mmol/d) and a protein intake of about 30 g/d.
6. Consume vegetable proteins in the form of grain products and legumes in amounts corresponding to about 40 g/d.
7. Consume fruits and vegetables daily, taking care to avoid foods containing very high quantities of oxalate.
8. Follow the USDA Dietary Guidelines for Americans for guidelines on overall intake of carbohydrates and fat.
9. Avoid vitamin D supplements if possible; take vitamin C supplements in amounts not exceeding 1500 mg/d; avoid vitamin B6 deficiency.
10. As much as possible, use fresh or frozen products rather than prepacked or precooked foods. Otherwise modulate the use of precooked food according to the content of sodium chloride and other nutrients listed in the label.
Thanks for writing,
Timothy S. Harlan, MD, FACP