Possible causes for the low prevalence of pediatric urolithiasis.
OBJECTIVE
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.
Miyake
O
O
Department of Urology, Osaka University Medical School, Suita, Japan.
Yoshimura
K
K
Tsujihata
M
M
Yoshioka
T
T
Koide
T
T
Takahara
S
S
Okuyama
A
A
D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D002129:Calcium Oxalate / Q000032:analysis*; D002648:Child; D002675:Child, Preschool; D003460:Crystallization; D006801:Humans; D008297:Male; D015995:Prevalence; D014545:Urinary Calculi / Q000453:epidemiology* / Q000652:urine*
D002129:Calcium Oxalate