Renal Stones (Kidney Stones)
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Renal stones – more commonly called kidney stones – develop when a collection of minerals normally found in the urine form a small "stone" in the urinary tract. The stone – actually a crystal – can cause pain, block urine flow and, in rare cases, cause long-term kidney problems if it is not recognized and treated promptly. Stones are more common in adults than in children. Most often, children who develop kidney stones have another condition that is causing them. Still, any child can develop the stones.
Kidney stones occur in about one in 20 people at some point in their life.
Children are less likely to get kidney stones, but there are factors that increase a child's chance of developing them. They include:
- A family or individual history of kidney stones. Some types of kidney stones run in families. Children who had a kidney stone in the past have the highest risk of developing another one.
- Not drinking enough water or fluids. Drinking a small amount of fluids means the kidneys produce less urine, which increases the concentration in the urine of the substances that form stones.
- Drinking sugary or caffeinated drinks or sport drinks, or eating a diet high in salt
- Eating a diet that features a small amount of carbohydrates – called a ketogenic diet, sometimes used to treat seizure disorders
- Having cystic fibrosis
- Having congenital abnormalities in the kidneys, ureters or bladder
A kidney stone usually forms when substances that are normally found in the urine – such as calcium, oxalate, cystine or uric acid – are at high concentrations in the urine.
The substances form crystals, which become anchored in the kidney and gradually increase in size, forming a stone. Kidney stones range in size from a few millimeters to, in rare cases, several inches. Very small stones (less than 5 millimeters) can usually pass through the urinary tract and the urethra on their own; larger stones usually require treatment.
Sometimes, very small stones can pass through the urinary tract without problems or symptoms. However, other stones can cause symptoms. Some of those include:
- A pain that begins in the side or back and then may spread to the lower abdomen and groin area as stones move through the urinary tract
- Pain that comes and goes in waves
- Blood in the urine, making it reddish or brownish
- Nausea and vomiting
- Needing to pee urgently
- Fever or chills
Larger stones can be quite painful and may block the flow of urine and cause other problems in the urinary tract.
If your child has symptoms of a kidney stone, you should visit the doctor as soon as possible. The doctor or a nurse will do an exam and order urine testing.
If the exam and urine tests suggest a stone is possible, the medical team arranges an imaging test. That might be an ultrasound, an X-ray or a computed tomographic, or CT, scan. That scan produces images of parts of the body using X-rays and a computer. The imaging tests can show the exact size and location of the stone, which can guide the medical team in the appropriate treatment.
Most stones work their way out of the body without much treatment, usually within 48 hours. Your child's doctor will likely suggest your child drink plenty of water and may prescribe a pain medicine – although over-the-counter medicines like ibuprofen or acetaminophen are often enough to deal with pain from small stones.
Your child's doctor likely will have you strain your child's urine to be able to recover any stone that passes. This is important because the medical team will want to send any stone to a lab for testing. Knowing what the stone is made of – calcium, uric acid or other minerals – guides treatment.
Some larger kidney stones may require treatment at the hospital. Your child may be given intravenous pain medications and fluids, sometimes for several days, until the stone passes. Or, the medical team might need to use shock waves or sound waves to break the stone into smaller pieces to allow it to pass out of the body. The team might also use a device with a small tube that can be placed into the urethra and into the bladder and remove the stone or break it into smaller pieces.
In rare cases, if the stone is especially large or is in or near the kidneys, surgery may be required.
Children who develop a kidney stone have a higher chance of developing them again.
There are ways to prevent kidney stones. Recommendations can vary depending on the type of stone your child has had. In general, children should:
- Drink plenty of fluids, especially water. That can decrease the chances of all type of kidney stones forming
- Eat a low-sodium (low-salt) diet
- Get enough calcium, but not too much
- Eat potassium-rich foods, like fresh fruits and many vegetables
- For some stones, avoid certain foods with large amounts of oxalate – including beet and turnip greens, rhubarb, strawberries, chocolate, parsley and spinach
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If your child has been diagnosed, you probably have lots of questions. We can help. If you would like to schedule an appointment, refer a patient or speak to our staff, please call our offices.