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.
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).
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.
Once a stone has passed, it is analyzed to determine its chemical composition. Different types of stone have different causes.
Our nephrologist may order additional metabolic and blood tests based on your child’s history and physical examination.
Our geneticist may order blood tests to determine if your child or your child’s biological family has a genetic predisposition for stone disease (see more below).
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.
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.