Urolithiasis in the first year of life.

Data on urolithiasis (UL) in infancy are limited. The objective of this study was to increase awareness of infant UL and to investigate the influence of possible risk factors in this very specific age group. Nonfasting, second-voiding urine samples were obtained to test for urinary excretions of calcium, oxalate, citrate, magnesium, uric acid, and creatinine. Blood analysis included calcium, phosphate, magnesium, uric acid, creatinine, sodium, potassium, chloride, and alkaline phosphatase. Patients received follow-up testing every 1-2 months; serial ultrasonography was used to track UL status. Fifty infants with a median age of 5 months were enrolled in the study. Hypercalciuria was detected in 9/47, hyperoxaluria in 5/39, hypocitraturia in 4/31, and cystinuria in 2/50 infants. We identified at least one metabolic abnormality in 46% of our patients; no metabolic abnormality was identified in 27 infants. Within a mean follow-up period of 14 months, 17 infants became stone free, stones increased in number in ten patients and decreased in number in 16, and recurrence was detected in seven. This study showed that UL could be detected in very early life, even in the newborn period, and could be the source of late childhood/adulthood UL. Infants with nonspecific symptoms such as restlessness may have UL and should undergo ultrasonographic examination. Metabolic evaluation of UL in this specific age group carries some diagnostic challenges, e.g. unsatisfactory data regarding normal ranges of urinary mineral excretion, and collection of 24-h urine samples.