Current Environment:

In recent years, there has been a steep and steady increase in the incidence of kidney stones in the pediatric population. Based on this increase, Boston Children's Hospital established a Kidney Stone Program in 2007 to help manage this influx.

Co-directors Caleb Nelson, MD, MPH; Bartley Cilento, MD, MPH; and Michelle Baum; MD, answer questions about why kidney stones are becoming more common in children, as well as treatment options and prevention tips.

How many patients are seen in the Kidney Stone 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. We now have four Kidney Stone Clinics each month in several locations: two in Boston, one in Waltham, and one in Weymouth. We plan to expand to our North Dartmouth satellite in the near future.

What do you think is causing this increase?

Dr. Nelson: There may be a number of reasons. Children are becoming less physically active, 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. Kidney 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 kidney-stone 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 with kidney stones?

Dr. Cilento: Treatment is determined based on the size, location, number and composition of the kidney 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 is 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. We perform 24-hour urine-stone risk profiles to understand fully the risks for kidney stones, and we can use these profiles to follow the impact of our medical treatments and the reduction of risk as a result of treatment.

What's the best way to prevent kidney-stone 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 prevent crystals from forming in the urine and to help substances dissolve in the urine. After a child has his first stone and we complete our initial evaluation, we like to see the child twice a year. We check to see how much fluid the child is drinking compared to our set goals, monitor symptoms, and do follow-up urine and blood tests. We assess for development of new stones by follow-up ultrasound or, where indicated, low-dose, non-contrast CT.

An important prophylactic component in the near future will be identification of a genetic cause of kidney stone disease.

When should a child see a specialist?

Dr. Nelson: All children with proven or suspected kidney stones should be seen by urology and nephrology. This is a potentially life-long condition that needs thorough investigation to reduce the risk of long-term issues.