The kidneys function to remove waste and extra fluid from the body. Sometimes crystals can precipitate out of the urine and clump together to form kidney stones. There are many causes of kidney stones, the most common being chronic dehydration. As opposed to adults, children are more likely to have an underlying metabolic abnormality causing their stones; thus, all children with a history of a stone in the urinary tract should have a full evaluation. Children who have a diet high in protein and salt or have a family history are also at increased risk of developing a kidney stone.
Stones form in the kidney and, if small enough, travel down to the bladder and are voided out. A stone can get stuck or held up anywhere along this path. Children with kidney stones may have blood in the urine, intermittent pain, or no symptoms at all. Even stones without symptoms must be managed surgically or watched very closely until they pass. When stones get stuck in the urinary tract, they can cause pain, nausea and vomiting, which is severe and intermittent in nature (renal colic). The pain is usually relieved as the stone moves down and temporarily relieves the obstruction and back pressure on the kidney. If a child has a fever or signs of infection with a stone that is blocking the urinary system, the urine is temporarily diverted by either a stent that is placed in the operating room and lies inside the body or by a percutaneous nephrostomy tube that is placed through the back directly into the kidney.
Children who present with signs and symptoms of stones are often evaluated with various imaging modalities such as an X-ray, ultrasound or CT scan. Blood work and urine tests are also usually ordered.
Stones are treated with observation, medical management or interventional therapy, including extracorporeal shock wave lithotripsy and/or surgery. Surgery can include ureteroscopy (using a very small telescope without any incisions) and percutaneous approaches through the back. Very rarely open or laparoscopic surgery is needed. Sometimes a stent is left in place to allow the ureter to dilate for the stone to pass spontaneously or to allow for easier ureteroscopy. The approach depends on the size, location and type of kidney stone. Whenever possible, stones are collected and sent for stone analysis. After the stone has been treated, the focus is on stone prevention. A full workup includes testing of a 24-hour urine collection and blood tests. This is sometimes done in partnership with our pediatric nephrology (medical kidney's doctor) colleagues.