Though there isn't a reliable tracking system to count each case, urologists are noticing a steep increase in the incidence of kidney stones in the pediatric population. In 2007, Boston Children's Hospital established a Pediatric Kidney Stone Center to help manage this influx.
Here, the center's co-directors Caleb Nelson, MD, MPH, Bartley Cilento, MD, MPH, and Michelle Baum, MD, talk about why kidney stones are becoming more common in children.
How many patients are seen in the clinic?
Dr. Nelson: A few years ago, we'd see a new patient about once a month. Now it seems like we see new cases every week.
What do you think is causing this increase?
Dr. Nelson: There may be a number of reasons. Children are getting less physical activity, which is contributing to an increased incidence of obesity. Obese people are more likely to get stones, although both obese and non-obese children and adults can get them. We don’t know if obesity itself causes stones, or is just a marker for other factors that cause stones. Diet is a factor, as many children get too much salt, eat highly processed foods and don't drink enough water. Stones form when there's too much of the stone-forming material and not enough water in the urine, so dehydration is a major contributor.
What are typical symptoms?
Dr. Cilento: Symptoms may vary from none, in the case of "silent stones," to excruciating pain due to urinary obstruction. Most obstructing stones cause pain, nausea and vomiting. In older children, flank or back pain is typical. In younger children, symptoms may be vague and they may not be able to pinpoint the location of their pain. For all children, blood in the urine is a key tip-off and any child with pain accompanied by blood in the urine should be evaluated.
What are the treatment options for patients?
Dr. Cilento: Treatment is determined based on the size, location, number and composition of the stone(s). In many cases, they can be passed spontaneously without any surgical treatment, since children can pass stones that are relatively large, compared with adults. Other times, it's necessary to remove them. The most common treatment is extracorporeal shock wave lithotripsy, where a noninvasive device is used to send shock waves through the skin into the body and fragment the stone.
Dr. Baum: We also do a metabolic evaluation and take a urine sample to assess for factors that contribute to stone formation, such as increased levels of calcium in the urine. We perform blood tests to look for other risk factors. Once the stone is passed or removed, we perform a chemical analysis to identify its type. This can provide important clues about why it formed.
What's the best way to prevent recurrence?
Dr. Baum: We prescribe individualized treatment plans for all our patients, including high fluid intake and a no added salt diet. Medications may be prescribed to help dissolve the stones or prevent new ones. After a child has his first stone and we've completed our initial evaluation, we like to see him twice a year. We check to see how he's drinking, monitor his symptoms and do follow-up urine and blood tests. We assess for development of new stones by follow-up ultrasound.