Kidney Stones

In kidney stone disease, or nephrolithiasis, stones (calculi) are present in the urinary tract. A kidney stone is a solid piece of material that forms in the urine when normal urine substances become highly concentrated.  These normal substances include calcium, oxalate, magnesium and phosphorus. 

Kidney stones may grow in quick spurts or very slowly over time. They can cause sudden and severe pain. Any child who has had a kidney stone is at increased risk of developing another stone in the future.

The four main types of kidney stones are:

Calcium Stones 

These are the most common type of kidney stones.  They occur in two major forms − calcium oxalate and calcium phosphate.

Cystine Stones 

Result from a genetic disorder where cystine leaks through the kidneys into the urine. 

Uric Acid Stones 

Form when the urine has too much acid in it. A diet rich in animal proteins may contribute to this kind of stone.

Struvite Stones 

Form when someone has frequent urinary tract infections.

Factors that place a child at increased risk for developing kidney stones are:

  • Family history of stones
  • Decreased water intake or long periods of dehydration
  • Repeated urinary tract infection
  • Diet high in sodium and/or protein
  • Obesity
  • Decreased activity level
  • Defects in the urinary tract
  • Use of certain medications

    Children with certain conditions are more prone to having recurrent kidney stones. Such conditions include:

    Urinary tract infections: Urea is a waste product found in urine. Some types of infecting bacteria break urea down into substances that form stones.

    Defects in the urinary tract: These may create areas of slow urine flow where stone-forming substances have a chance to settle and form stones.

    Cystic fibrosis: Faulty absorption in the intestine and other factors lead to too much oxalate in the urine, predisposing a child to form stones.

    Inflammatory bowel disease: Increased intestinal absorption of oxalate leads to high amounts of oxalate in the urine, with an increased chance of stone formation. Patients who have had a partial bowel removal are more prone to dehydration, further increasing their risk of developing kidney stones.

    Seizures: Certain anti-seizure medications or an anti-seizure (ketogenic) diet increase the risk of stone formation.

    Hypercalciuria, hyperoxaluria and cystinuria: These conditions cause elevated levels of stone-forming substances such as calcium, oxalate and cystine in the urine, increasing the likelihood of stone formation.

    Neurogenic bladder as seen in spina bifida, and other neurological disorders such as Duchenne muscular dystrophy: Children with neurological conditions affecting normal bladder function and control have a higher likelihood of delayed urination, allowing urine to sit longer and creating an opportunity for stones to form. These children are also at higher risk for repeated urinary tract infections from incomplete bladder emptying.

    Decreased activity: Any child who is unable to move around − for instance, one confined to a wheelchair − is at increased risk of developing kidney stones.

    A child may have a sudden, severe pain in the side of the body. The pain can spread out to the belly, groin or genitals. It may be so painful that the child is unable to find a comfortable position. Other symptoms include:

    • Pain with urination
    • Blood in the urine
    • Frequent / persistent urinary tract infection
    • Urinary urgency and/or frequency
    • Nausea / vomiting
    • Fever

    Kidney stones are often diagnosed in the Emergency Department, when children come in with severe belly or side pain. The following may be used to diagnose and locate stones.

    Medical History

    Physical Examination

    Radiology

    As part of the Image Gently campaign, doctors at Cincinnati Children’s make every effort to minimize how much radiation children receive.

    Renal ultrasound: The most common radiologic test used to diagnose a urinary tract stone is an ultrasound. The technician slides a hand-held device known as a transducer across the child’s skin. This is a painless test using sound waves to take pictures of the kidneys, ureters and bladder. The images created may show the location of any stone(s).

    CT scan: The child lies flat on a platform that slides into a doughnut-shaped device.  X-ray technology is used to create three-dimensional (3-D) pictures of sections of the body to determine the location(s) of the stones(s).  CT scans for kidney stones may require the injection of contrast dye to aid in locating the stone(s). The lowest possible amount of radiation will be used to provide the necessary diagnosis.

    Kidney, ureter, bladder (KUB) X-ray. A quick, simple X-ray uses external radiation to assess your child’s abdomen and view the urinary tract and the presence of any stone(s).

    Urine Testing (Litholink)

    Various urine tests such as a urine analysis and urine culture can be used to check for the presence of a urinary tract infection. Other tests such as a 24-hour urine collection can measure the levels of chemicals that can form stones. 

    Stone Analysis

    Once a stone has passed, it is analyzed to determine its chemical composition. Different types of stone have different causes.

    Blood Tests

    Our nephrologist may order additional metabolic and blood tests based on your child’s history and physical examination.

    Genetic Testing

    Our geneticist may order blood tests to determine if your child or your child’s biological family has a genetic predisposition for stone disease.

    Dietary Consultation

    Diet is often linked to stone formation. Based on your child’s testing and stone analysis, he or she may be referred to a dietitian for a consultation. The dietitian will evaluate your child's daily intake of calcium, vitamin D, fruits, vegetables, salt and protein to determine if your child's diet is related to his or her stone formation.

    High urine concentrations of various elements such as calcium, phosphorous and oxalate can lead to kidney stones. In children who are susceptible, certain foods may increase the likelihood of stone formation.

    Genetic Testing

    Genetics can play an important role in kidney stone disease. Around 35 to 40 percent of people who form kidney stones have family members who also had stones. People who inherit this trait often begin forming stones early in life and tend to have repeated episodes. Our geneticist may order blood tests to determine whether your child or your child’s biological family has a genetic predisposition for stone disease.

    The genetics of kidney stone formation is complex and we are learning more about it all the time. Examples of conditions with a genetic basis include:

    • Hypercalciuria (excessive amounts of calcium in the urine), which may be caused by defects in a number of genes. Elevated urine calcium increases the likelihood of stone formation.
    • Hypocitraturia (too little citrate in the urine) may also have a genetic basis. Citrate prevents kidney stones, so not having enough of it may increase a person’s risk of developing stones.
    • Primary hyperoxaluria results from a liver enzyme defect causing the production of large amounts of the chemical oxalate, which, in turn, results in high levels of oxalate being eliminated in the urine. Oxalate combines with calcium to form the most common type of kidney stone.
    • Cystinuria is an inherited disease in which the kidney excretes too much of the amino acid cystine into the urine, resulting in the formation of cystine stones.  

    The treatment for kidney stones depends on the size, what it is made of, and whether they are causing symptoms or blocking the urinary tract.  Small stones will likely pass on their own without treatment, but will often require pain control and encouragement to drink a lot of extra fluids to help the stone pass.  Larger stones or ones that block the urine flow may require surgery or hospitalization.

    Extracorporeal Shock Wave Lithotripsy

    Extracorporeal shock wave lithotripsy (ESWL) uses focused acoustic shock waves to crush kidney stones. The smaller pieces can travel through the urinary tract more easily and eventually pass through the body.  ESWL is done under anesthesia and usually takes about 45 minutes.  No incision is needed.

    Ureteral Stent

    Your child may need a ureteral stent if he or she has a blockage or narrowing of the ureter. The ureter is a slim, muscular tube that conducts urine from the kidney to the bladder. A ureteral stent is a soft, hollow tube that is placed temporarily in the ureter to hold it open. General anesthesia is used for this procedure. With the stent in place, the child may move around normally but should not do any strenuous activities.

    Percutaneous Nephrolithotripsy

    This is a surgical procedure for removing medium to large stones from the kidney. It is done using general anesthesia. First, a tube is inserted into the kidney through an incision in the child’s back. Then, with the help of a very thin, fiberoptic instrument called a nephroscope, the doctor locates and removes the stone. This procedure may be combined with laser treatments to break up large stones for easier removal and with nephrostomy tube placement.

    Nephrostomy Tube Procedure for Kidney Stones

    A nephrostomy tube is a small, flexible tube that is surgically inserted through the skin into the kidney to drain urine. The urine collects in a bag outside the body. This procedure may be needed to prevent kidney damage and infection if a kidney stone is blocking normal urine drainage, or temporarily after a large stone is removed. Nephrostomy tubes are placed by specialists, using general anesthesia. The procedure takes about an hour. Once the blockage has been relieved, the tube can be removed.

    Managing Pain

    Kidney stones can be cause severe pain as they travel from the kidney into the ureter, the narrow tube that drains the urine from the kidneys into the bladder.  This pain, called renal colic, may cause nausea and vomiting. You can give your child Tylenol as directed for pain. Contact your doctor if your child does not get relief from the Tylenol.  


    The most important way to prevent kidney stones from forming is drinking a lot of fluids. This keeps the urine dilute, and stones are less likely to form.  Your doctor will also order a 24-hour urine collection that a special lab, Litholink, will evaluate to see what kind of stones your body is making.  From that evaluation the doctor can decide what medications or treatments you may need to help kidney stones from forming.

    For more information, contact the Cincinnati Children’s Pediatric Stone Center at 513-803-7625.

    Last Updated 03/2016