A kidney stone forms when substances in the urine become highly concentrated. The causes can include a blockage in the urinary tract, a genetic tendency, drinking too little water or eating too much salt, a bacterial infection in the urinary tract, or a condition that prohibits the body from effectively digesting food or certain seizure medications.
Pediatric kidney stones vary in shape and size, from the size of a grain of sand to the size of a golf ball (in extreme cases). When these stones are larger than the urinary tube, they can get lodged in the urinary tract and cause intense pain.
Stones pass from the kidney to the ureter (the tiny tube that connects the kidney to the bladder). Some kidney stones are small enough to pass without being noticed. Others are larger than the tube and become stuck when trying to pass through. This leads to a urine backup in the kidney, ureter, bladder or the urethra (which takes urine from the bladder out of the body) – wherever the stone is stuck.
Calcium stones are the most common type of kidney stone in children is made of calcium oxalate or calcium phosphate. Calcium in the diet does not increase the risk of this type of stone.
Cystine stones are a side effect of a genetic disorder called cystinuria. The child’s kidneys leak large amounts of an amino acid called cysteine. Cysteine crystals can form stones.
Struvite stones can form after an infection in the upper urinary tract. They develop suddenly and become large quickly. They often affect children whose urinary tracts did not develop normally.
Uric acid stones form when a child’s urine contains too much uric acid, due to inherited conditions or diet. The body creates uric acid when it breaks down substances called purines, a natural chemical compound found in many foods and drinks.
There are many causes of kidney stones, but the most common reason is eating too much salt and not drinking enough water. In fact, the formation of a kidney stone is actually multiple small salt crystals sticking together and growing until it becomes a visible stone.
To describe how kidney stones form, ask your child to imagine sea water evaporating and leaving salt crystals behind. When these stones become large enough to become painful, they may even block the kidneys or the tubes (ureters) that carry urine.
Depending on the size and severity of your child’s kidney stone, we typically recommend this series of treatment options:
Many things have been recommended to prevent kidney stones in adults, including changing intake of water, sodium salt, acidity (pH), calcium, citrate, and oxalate. But children are not just “little adults”. Before any dietary changes are made, it is extremely important to have 24 hour urine testing to find out the best dietary recommendations for your child’s specific case.
This is extremely important, as some dietary recommendations to prevent stones in adults can actually hurt children and can even make the child create MORE kidney stones. And children are growing, so their dietary needs for normal growth must be considered in the prevention recommendations.
Along with any relevant medical history, results from initial blood and urine tests will guide the pediatric urologists and nephrologists to recommend any additional testing or medications to prevent future stones.
The procedures will be discussed in more detail at your clinic visit. Sometimes, a temporary hollow drainage tube the size of a spaghetti noodle (called a double J stent) needs to be placed before or after the surgery.
American Board of Pediatrics/Nephrology