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Published on: October 12, 2017
Possible causes for the low prevalence of pediatric urolithiasis
O Miyake1, K Yoshimura, M Tsujihata
1Department of Urology, Osaka University Medical School, Suita, Japan.
Insights
Pediatric urine macromolecules (UMMs) show stronger inhibition of calcium oxalate (CaOX) crystal aggregation than adult UMMs. This difference, linked to higher glycosaminoglycan (GAG) levels in children, may explain lower CaOX urolithiasis incidence in pediatric populations.
Area of Science:
- Nephrology
- Urology
- Biochemistry
Background:
- Pediatric urolithiasis (kidney stone formation) has a lower incidence compared to adults.
- Urinary macromolecules (UMMs) play a role in inhibiting stone formation.
- Understanding differences in UMMs between age groups is crucial for explaining incidence disparities.
Purpose of the Study:
- To investigate the differential inhibitory effects of pediatric and adult urinary macromolecules (UMMs) on calcium oxalate (CaOX) crystallization.
- To identify factors contributing to the lower incidence of CaOX urolithiasis in children.
Main Methods:
- Comparison of CaOX crystallization inhibition in original urine and UMM-depleted urine between children and adults.
- Measurement of CaOX crystal growth and aggregation inhibition by isolated UMMs.
- Analysis of UMM composition, focusing on glycosaminoglycans (GAGs).
Main Results:
- Original pediatric urine exhibited stronger CaOX crystallization inhibition than adult urine.
- UMMs from children showed significantly greater inhibition of CaOX crystal aggregation compared to adults.
- Pediatric UMMs contained higher concentrations of glycosaminoglycans (GAGs) than adult UMMs.
Conclusions:
- The reduced incidence of CaOX urolithiasis in children may be due to enhanced CaOX crystal aggregation inhibition by pediatric UMMs.
- Higher GAG concentrations in pediatric UMMs are likely responsible for their superior inhibitory activity.
- These findings highlight the protective role of specific urinary components in preventing kidney stone formation in children.
Objectives:
To determine why the incidence of pediatric urolithiasis is less than that of adult urolithiasis, we investigated the difference in inhibition of calcium oxalate (CaOX) crystallization between pediatric and adult urinary macromolecules (UMMs).
Methods:
Urinary parameters in relation to urolithiasis, the inhibition of CaOX crystallization of original urine and urine from which UMMs (greater than 3 kDa) had been removed, and the inhibition of CaOX crystal growth and aggregation of UMMs alone were measured. These inhibitory activities were compared between children and adults.
Results:
In the original urine, the inhibition of CaOX crystallization was significantly stronger for children than for adults, but was the same in urine from which the UMMs had been removed. The inhibition of CaOX crystal growth by UMMs alone showed no significant differences between children and adults; their inhibition of CaOX crystal aggregation was significantly stronger for children than for adults. Much more glycosaminoglycan (GAG) was included in pediatric UMMs than in adult UMMs, although there was no difference in UMM concentration between urine from children and urine from adults.
Conclusions:
The lower incidence of CaOX lithiasis in children may be attributed, among other factors, to the stronger inhibition of CaOX crystal aggregation by pediatric UMMs, which in turn might be affected by the higher concentration of GAGs in children's urine.
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