Ultrasound of urinary system and urinary screening in 14 256 asymptomatic children in China

Aim: The aim of this study is to assess the characteristics of urinary system diseases and the role of the ultrasound screening and urinalysis screening for chronic kidney disease (CKD) in asymptomatic children in China. Methods: Between September 2008 and November 2008, 14 256 children excluding those with obvious symptoms and signs were enrolled in our study. All the subjects accepted ultrasound and urinary screening. A case–control study was performed to evaluate the relative risk of having stones in those children exposed to melamine formula. Results: Of the enrolled children, 6.10% (869 of 14 256) showed abnormalities, of which 409 (2.87%) were established by ultrasound, 572 (4.01%) by urinalysis and 112 (0.79%) by both ultrasound screening and urinalysis. The abnormalities included congenital anomalies of kidney and urinary tract, urinary stones and/or hydronephrosis, leucocyturia and haematuria and/or proteinuria. Children exposed to melamine formula were 5.17 times as likely to have kidney stones as children exposed to no‐melamine formula (95% confidence interval, 3.28–8.14; P < 0.001); the probability of kidney stones in melamine‐fed infants were 6.28 times as likely as those no melamine‐fed (95% confidence interval, 3.71–10.65; P < 0.001). Conclusion: Ultrasonography and urinalysis could complement each other and play important roles in the early diagnosis of anomalies of the urinary system, but urinalysis is a more cost‐effective screening tool for CKD in children in China. Exposure to melamine‐contaminated formula associated with urinary stones, especially in infants, was significantly higher than the control group.