Children with asthma are four times more likely to have kidney stones than children without asthma, Cleveland Clinic researchers found.
The study, “Co-Occurrence of Asthma and Nephrolithiasis in Children,” was published in the journal PLos One.
Kidney stones occur when urine contains more crystal-forming substances — such as calcium, oxalate and uric acid — than the fluid in the urine can dilute. The urine may also lack substances that prevent crystals from sticking together, creating an ideal environment for stones to form.
Asthma is the most common chronic disease in childhood, affecting 8.3% of youngsters, according to the Centers for Disease Control (CDC). It is characterized by alterations in the epithelial ion channels that regulate the movement of fluid and ions in the lungs. The cause of the alterations are inflammatory reactions to allergens, or allergic substances.
Both the incidence of asthma and kidney stones in children seem to be increasing, with studies showing that one in three children under 12 with kidney stones has asthma.
Manoj Monga and colleagues at the Cleveland Clinic used electronic medical records at the clinic to investigate whether children with asthma had more kidney stones than children without asthma. They also wanted to see whether asthma patients with kidney stones had clinical characteristics and urine profiles that pointed to mechanisms of stone formation.
Monga is director of the Stevan B. Streem Center for Endourology and Stone Disease in the clinic’s Glickman Urological & Kidney Institute.
Researchers included 865 children with kidney stones, between 6 months and 18 years old, in their analysis. The information they used included asthma diagnosis, medication, age, gender, race and body mass index (BMI). They also analyzed 24-hour urine samples.
The team compared clinical information on 142 children who had both asthma and kidney stones with information on children who had kidney stones only.
Children with asthma were found to be four times more likely to have kidney stones than the general pediatric population. Similarly, children with kidney stones were found to be four times more likely to have asthma.
Researchers also found that children with both asthma and kidney stones were more likely to be on a combination of inhaled corticosteroid plus a long-acting beta agonist inhaler than children with asthma who had no kidney stones.
There were no statistically significant differences in 24-hour urine profiles between children with both asthma and kidney stones and those with kidney stones only.
“While obesity is thought to predispose children to kidney stones, the association between asthma and kidney stones in this study was not related to BMI,” Monga said in a news release. “To date, theories regarding kidney stone formation have centered around abnormalities in urinary chemistries. As no differences were identified in this study, alternative links between the two diseases, perhaps involving inflammatory pathways or epithelial dysfunction, will need to be explored.”
Researchers said studies are needed to further assess the relationship between asthma and the formation of kidney stones in children.
“These results clearly demonstrate a link between the conditions in a large pediatric population,” said Serpil Erzurum, MD, a study co-author. “A better understanding of the link between the diseases might uncover new genetic or biochemical pathways and could lead to better interventions to prevent painful stones from developing in pediatric asthma patients,” added Erzurum, chair of the Lerner Research Institute at Cleveland Clinic and holder of the Alfred Lerner Memorial Chair in Innovative Biomedical Research.