Children with asthma are 4 times more likely to have kidney stones than those without asthma, and vice versa, according to a study published online in the medical journal PLoS One.1
“We evaluated children with kidney stones and children with asthma,” says co-investigator Serpil Erzurum, MD, chair of the Lerner Research Institute at the Cleveland Clinic, Cleveland, Ohio. “In either case, asthma and kidney stones are associated with each other.”
Data for the retrospective study were gleaned from the Cleveland Clinic’s electronic medical records of pediatric patients aged between 6 months and 18 years with a diagnostic code of either asthma or kidney stone, from 2000 to 2014. A total of 865 patients had a diagnosis of nephrolithiasis and 36,518 patients had a diagnosis of asthma.
The prevalence of kidney stone alone was 0.08% compared with 6.79% for asthma alone. However, the prevalence of kidney stones in children with asthma was 6-fold higher. “To the best of our knowledge, this is the first time such a connection has been described. It is important that pediatricians have this knowledge base when caring for children,” says Manoj Monga, MD, director of the Stevan B. Streem Center for Endourology and Stone Disease in the Glickman Urological and Kidney Institute at the Cleveland Clinic and senior investigator of the study.
A surprising association
The Cleveland Clinic doctors were inspired to undertake the evaluation for a number of reasons, including the understanding that in children with cystic fibrosis, there is an increased incidence of kidney stones, for unclear reasons.2 “We thought that asthma, being an inflammatory airway disease, might be another population that could have similar findings,” Erzurum says. “The airways and the tubules of the kidney have surprisingly similar functions.”
Inflammation is a common underlying process in asthma and kidney stones.3 Nevertheless, the researchers were surprised to find a dramatic association between the 2 diseases. “By eventually understanding the reason for this co-occurrence, we will better understand asthma and kidney stones,” Erzurum says. “Hopefully, this will open up some basic biology that we can understand about both disorders, resulting in new ideas for studying these 2 diseases.”
The investigators did not find any meaningful differences in patient characteristics or demographics, including age, sex, and body mass index (BMI). However, socioeconomic factors were not evaluated. There also was no difference in inhaled beta agonists, inhaled corticosteroids, or any antiasthmatic medication use among asthma patients, with or without a stone diagnosis. On the other hand, asthma-stone patients were more than twice as likely to be on a combination inhaled corticosteroid plus long-acting beta agonist than asthma patients without a stone (29.7% vs. 13.7%, respectively).
“Because this was a historical study looking at our database, we are limited in what we can conclude,” says Erzurum, holder of the Alfred Lerner Memorial Chair in Innovative Biomedical Research at the Cleveland Clinic. “It could be that some of this association is related to drugs or medications being taken by these children. But we did not find any evidence for that when we tried to compare by controlling for the drugs they were using for their asthma.”
Time to change protocols?
Asthma is a common diagnosis in children and kidney stones are also observed.4,5 “Both lead to discomfort,” Monga says. “Furthermore, parents miss work by staying home with their school-aged children.”
Based on the study, pediatricians should consider the co-occurrence of asthma and kidney stones.
Monga says it is too early for pediatricians to change their treatment protocols for treating asthma or kidney stones. Similarly, the results should not be overinterpreted. “If you are a child with asthma, you are likely to never have a kidney stone,” Monga says. “Kidney stones in childhood are still not that common. And if a child has kidney stones, there is nothing evidence based to consider this a process leading to asthma.”