A nationwide study of mass urine screening tests on Korean school children and implications for chronic kidney disease management

Since 1998, urine screening tests have been performed on school children in Korea. We report the findings of the screening program that analyzed patients with proteinuria and/or hematuria. Between 1999 and 2008, 5,114 children were referred to pediatric nephrologists at seven nationwide hospitals. Renal biopsies were performed on 1,478 children [28.79 % of total subjects; 26.77 % for isolated hematuria (IH), 9.09 % for isolated proteinuria (IP), and 51.19 % for combined hematuria and proteinuria (CHP)] who showed abnormal renal function, persistent hematuria and/or proteinuria for more than 6 months, nephrotic-range proteinuria, or those with underlying systemic diseases. Chronic glomerulonephritis (GN) was detected in 25 % of all visiting subjects. The most common findings in renal biopsies were immunoglobulin A (IgA) nephropathy in 38.97 %, mesangial proliferative GN in 24.29 %, and thin basement membrane nephropathy in 13.13 %. Compared with the relative frequency of renal diseases associated with urinary abnormalities, CHP (46.90 %) and nephrotic-range proteinuria (69.96 %) groups had more frequent GN than the others. Abnormal findings on renal ultrasound with or without Doppler scan were noted in 462 cases (suspected nutcracker phenomenon, 159; increased parenchymal echogenicity, 92; hydronephrosis, 75; simple cyst, 47). Mass urine screening tests could detect asymptomatic GN in its early stages. Initial aggressive diagnosis and treatment for CHP and nephrotic-range groups may prove helpful as interventions that delay chronic kidney disease progression. These findings may assist in the development of diagnostic and management guidelines for relatively mild urinary abnormalities, such as IH or low-grade IP.