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Incidence of hypocomplementemia in elementary and junior high school children with urinary abnormalities
M Murakami1, N Tatsuma, H Tsugu
1Department of Pediatrics, Nippon Medical School Hospital, Tokyo, Japan.
Insights
Screening for urinary abnormalities in schoolchildren found low serum complement (C3) in a few cases. Further testing for hypocomplementemic membranoproliferative glomerulonephritis (MPGN) in this context showed a low cost-benefit ratio.
Area of Science:
- Pediatric Nephrology
- Clinical Immunology
- Public Health Screening
Background:
- Urinary abnormalities are common in school-aged children.
- Screening programs aim to detect early signs of kidney disease.
- Serum complement levels, particularly C3, can indicate underlying glomerular inflammation.
Purpose of the Study:
- To evaluate the utility of measuring serum C3 levels in children identified with urinary abnormalities during school-based screening.
- To assess the prevalence of hypocomplementemic conditions, specifically Type I membranoproliferative glomerulonephritis (MPGN), in this population.
- To determine the cost-effectiveness of incorporating serum C3 testing into routine school urinary screening.
Main Methods:
- A large-scale school screening for urinary abnormalities was conducted.
- Serum C3 levels were measured in children with detected urinary abnormalities.
- Diagnostic workup, including histological examination and renal biopsy, was performed for select cases.
- Cost-benefit analysis was considered for the screening protocol.
Main Results:
- Out of 326,257 children screened, 2669 had urinary abnormalities.
- Three children exhibited serum C3 levels more than three standard deviations below the mean.
- One child was diagnosed with Type I MPGN; two others with transient abnormalities and low C3 did not undergo biopsy.
- The cost-benefit ratio for serum C3 testing in this screening setting was deemed low.
Conclusions:
- Routine serum C3 testing during school urinary abnormality screening has limited significance and a low cost-benefit ratio.
- The findings may reflect the incidence of persistent hypocomplementemic MPGN in Japan.
- Further investigation is warranted to optimize screening strategies for pediatric kidney diseases.
Abstract:
Abnormalities were detected in 2669 of 326,257 elementary and junior high school children (169,856 males and 156,401 females) who were screened at school for urinary abnormalities. Serum complement (C3) level was measured in all 2669 children having urinary abnormalities (811 males, 1856 females). Three had a serum C3 level that was more than three standard deviations below the mean value. Type I membranoproliferative glomerulonephritis (MPGN) was diagnosed on histological examination in one of these three children, while the other two did not undergo renal biopsy because they had serum C3 levels of 40 and 44 mg/dL, respectively, and because their urinary abnormalities were transient. It was considered that there is not much significance in testing the serum complement in the urine screening done at school and the cost/benefit ratio is low. The results appeared to reflect the frequency of persistent hypocomplementemic MPGN in Japan in recent years.