Hypocomplementaemia and membranoproliferative glomerulonephritis in school urinary screening in Japan.

Yearly screening was performed from 1980 to 1985 in 92,934 school children in the first to ninth grades; a total of 370,148 urine specimens were evaluated. In 1980 and 1981, urinary abnormalities were detected in 0.23% of children examined; the detection rates at the third level of screening for proteinuria, haematuria and haematuria with proteinuria were 0.03%, 0.15% and 0.06%, respectively. The criteria for haematuria were changed from 6 to 20 red blood cells/high power field in the second screening after 1981. Between 1982 and 1985, the equivalent rates were 0.02%, 0.07% and 0.03%, respectively, and the total abnormality prevalence was 0.13%. In 19 children the serum C3 level was below 53 mg/dl; in 5 of these it was below 30 mg/dl. Of these 5 children, 4 underwent renal biopsy and were diagnosed as having membranoproliferative glomerulonephritis.