Kidney stones are hard concretions of the minerals and other elements normally found in urine. The stone typically forms in the kidney before it passes down the tubes connecting the kidney to the bladder. Rarely, stones may form in the bladder.
While kidney stones can occur at any age, even in premature infants, most occur in teens, with teen girls having the highest incidence.
Types of Kidney Stones
There are many different types of kidney stones in children, but the most common one in the United States contains calcium in association with other materials. The stones range in size from a fraction of an inch to several inches, with most around ¼ - ½ inch in size.
Causes of Kidney Stones
In most children and teens, kidney stones are due to the diet and/or amount of fluid the child drinks. In some children, however, they are the result of a:
- Specific inherited problem
- Blockage of urine flow
- Kidney infection
Signs and Symptoms
The most common sign of a kidney stone in older children and teens is the sudden onset of pain in the back or side. The pain is usually constant and severe, and often causes nausea and vomiting
. This pain may move into the groin area as the stone passes down the urinary tract. Most of the time, this causes blood to appear in the urine
. Often this is only detectable by testing the urine for blood but sometimes it is visible to the naked eye.
Young children with kidney stones are usually unable to tell exactly where the pain is and just complain that their tummy hurts. A number of young children will have no pain at all and the stones are discovered during the evaluation of a urinary tract infection
or as an unexpected finding on an x-ray
or ultrasound study done for another reason.
How Is the Diagnosis Made?
While the location and severity of the pain and the presence of blood in the urine are suggestive of a kidney stone, the diagnosis rests on finding a stone in the urinary tract by an x-ray or an ultrasound. Sometimes, the diagnosis is made by capturing the stone in the urine after it has been passed.
Many stones can be seen with a simple x-ray of the abdomen and most can be seen with an ultrasound of the kidneys. A CT scan
can show the smallest stones but exposes the child to more radiation. If you or your doctor suspects your child has a kidney stone, he or she can help you decide what method is needed in order to make a diagnosis.
Once a stone is discovered, the initial goal is to help your child pass the kidney stone out of the urinary tract by drinking large amounts of water and other fluid. In a sense, they are trying to “flush it out.” If your child cannot keep fluid down because of the pain and nausea, it may be necessary to have the fluid given through an IV. Often, medicine is given to help reduce the pain.
Stones larger than a ½ inch may require surgery or lithotripsy to remove them. Lithotripsy uses a special machine to send sound waves into your child to smash the stone into much smaller pieces that can then be passed down the urinary tract. While it may sound scary, it is quite safe and doesn’t damage the kidney. Lithotripsy can even be done in small children, although a child may be put to sleep for the procedure.
The best treatment is to prevent new stones from forming. All children with kidney stones should:
- Drink a lot of fluid throughout the day
- Limit the salt in their diet
- Limit the amount of soda or soft drinks they consume
Your doctor may ask you to collect all the urine your child passes for 24 hours to test it for specific factors that may predispose your child to kidney stones. With this information, your doctor will better understand why your child formed a stone and be able to make specific dietary recommendations or prescribe certain medications to help prevent your child from making another kidney stone. Your doctor may also recommend that your child see a pediatric nephrologist
who has experience in treating children with kidney stones.