Urinary screening and urinary abnormalities in 3-year-old children in Japan.

In Japan, urinary screening for preschool children has been obligatory since 1961. The system was reconsidered and has been under review since 2012, because many problems in the system had been identified, and its usefulness was uncertain. In the process, the following were analyzed: (i) frequency of urinary abnormalities identified on screening; (ii) diseases identified from urinary abnormalities; (iii) clinical course of children found to have urinary abnormalities; and (iv) screening for asymptomatic urinary tract infection (UTI) as a way of screening for congenital anomalies of the kidney and urinary tract. A computerized literature search was conducted, and study reports issued by the Ministry of Health, Labour and Welfare study group, and data of Akita City and Chiba City were reviewed. The prevalence of abnormal results at the first urinalysis was high, but at the second urinalysis the prevalence decreased in the range 1/6-1/20. The prevalence of tentative diagnosis at the third urinalysis was similar to the school urinary screening results. Serious illness was not found in children who had hematuria alone. In contrast, diseases requiring immediate attention were found in children with proteinuria, although the prevalence of proteinuria was not high. The dipstick method for leukocyturia was inefficient. The importance of two consecutive urinalyses before detailed examination, the lack of usefulness of screening for hematuria in 3-year-old children, and the importance of proteinuria were confirmed. Screening for asymptomatic UTI using urinary leukocytes was very inefficient.