Introduction:
Urolithiasis diagnosed among children aged under 3 years of age concerns 20% of the total number of cases of urolithiasis in children. The symptoms of the disease are very nonspecific, with the major symptoms of abdominal signs, irritability or restlessness, which, however, may be asymptomatic. Objective: Investigation of frequency of the occurrence of risk factors, and the diversity of symptoms among children aged under 3 years.

Material and Methods:
A 3-year retrospective epidemiological analysis was performed among children under 36 months of age with confirmed urolithiasis, including data on neonatal and infancy risk factors that occurred, symptoms, laboratory and ultrasound results at the time of diagnosis.

Results:
70 children were qualified for the study: 35 boys and 35 girls. 37% of the children had a positive family history of urolithiasis. The most common risk factors were urinary tract infections (58%). Mean age at diagnosis was 10 months, and the symptoms of urolithiasis were present in 84% of cases. Metabolic anomalies were found in 31.4% of patients, while hypercalciuria occurred in 12.8%.

Conclusions:
Urolithiasis in children aged under 3 years is mostly diagnosed due to nonspecific abdominal symptoms. The most common risk factors are UTI. Metabolic anomalies occurred in over 30% of cases.