Evaluation of screening with urine dipsticks and renal ultrasonography for 3-year-olds in Chiba City over 30 years

Background Urinary screening for 3-year-olds cannot adequately detect congenital anomalies of the kidney and urinary tract (CAKUT). Methods Urinary screening for 3-year-olds was investigated over 30 years. Dipsticks for proteinuria, hematuria, glycosuria, leukocyturia, and nitrite at first screening, and dipsticks, urinary sediments, and renal ultrasonography at second screening were performed. Screening results were evaluated. Results The positive rates of proteinuria, hematuria, leukocyturia, and nitrite relative to 218,831 children at the first screening were 1.0%, 4.6%, 2.3%, and 0.88%, respectively. Thirty-seven glomerular disease, 122 CAKUT, and 5 urological disease cases were found. We detected 6 stage 3–4 chronic kidney disease (CKD) and 3 end-stage kidney disease cases, including 3 CAKUT, comprising 2 bilateral renal hypoplasia and 1 vesicoureteral reflux (VUR), and 6 glomerular diseases, comprising 4 focal segmental glomerulosclerosis and 2 Alport syndrome. The positive rates relative to 218,831 children and CKD detection rates for each tentative diagnosis of mild hematuria, severe hematuria, proteinuria and hematuria, proteinuria, and suspected urinary tract infection were 1.4% and 0.67%, 0.11% and 3.7%, 0.01% and 28.6%, 0.02% and 45.0%, and 0.08% and 9.7%, respectively. Among 14 VUR cases with significant bacteriuria, 13 were found by leukocyturia, 12 had grade ≥ IV VUR, and 10 had severe renal scars. Conclusions Nine stage 3–5 CKD cases comprising 3 CAKUT and 6 glomerular disease were found by urinary screening of 3-year-olds among 218,831 children. The combination of urine dipsticks including leukocyturia at the first screening and ultrasonography at the second screening appeared useful.