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How Significant Are Asymptomatic Gross and Microscopic Hematuria?

Thorough diagnostic evaluation is necessary for children with asymptomatic gross hematuria but not for children with asymptomatic microscopic hematuria.

Asymptomatic hematuria (gross or microscopic) is relatively common in children. The estimated prevalence of asymptomatic microscopic hematuria in children is 0.5% to 2.0%; the incidence of asymptomatic gross hematuria is not known. Because the clinical significance of asymptomatic hematuria is uncertain, the traditional approach is to pursue a thorough clinical investigation. To evaluate its clinical significance and determine when diagnostic evaluation is necessary, investigators at Indiana University prospectively evaluated 570 children who were referred for evaluation of asymptomatic hematuria.

Microscopic hematuria (defined as >5 red blood cells/high-powered field) was detected at routine exams. Diagnostic evaluation consisted of personal history (to exclude symptoms), physical exam, blood pressure measurement, and laboratory studies (including complete blood count, urinalysis, serum creatinine and C3 levels, creatinine clearance, protein and calcium excretion, and ultrasonography or intravenous pyelography). Streptozyme titers were measured when hematuria was of less than 6 months’ duration, antinuclear antibody assays were conducted in teenagers, and black children underwent hemoglobin electrophoresis. Urine cultures and renal biopsies were performed selectively (e.g., for persistent hematuria, hypertension, proteinuria, and decreased renal function).

Of 342 children with microscopic hematuria, no cause was discovered in 80%. The most common cause was hypercalciuria (16% of all patients). Four children had poststreptococcal glomerulonephritis, and 4 had structural abnormalities of the urinary tract.

Gross hematuria was a different story: Of 228 children, a cause was detected in 62%, including one Wilms tumor. Hypercalciuria without a history of stone disease was the most common cause (22% of patients), followed by IgA nephropathy (16%) and poststreptococcal nephritis (9%). Twelve patients were hypertensive, and 10 had structural abnormalities.

Comment: Because of the low incidence of significant findings in children with asymptomatic microscopic hematuria (without proteinuria), it seems rational and safe to simply follow such children and to evaluate them further only if hypertension, proteinuria, or other symptoms emerge. Gross hematuria, on the other hand, should always prompt a thorough investigation.

— Harlan R. Gephart, MD

Published in Journal Watch Pediatrics and Adolescent Medicine May 6, 2005

Citation(s):

Bergstein J et al. The clinical significance of asymptomatic gross and microscopic hematuria in children. Arch Pediatr Adolesc Med 2005 Apr; 159:353-5.

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