The prevalence of asymptomatic hematuria is approximately 0.5 to 2.0 percent in children. When gross or persistent microscopic hematuria is present, the cause usually is determined through a thorough evaluation. The clinical significance of asymptomatic hematuria has not been determined, and the usefulness of this evaluation is unclear. Bergstein and associates assessed the clinical significance of hematuria in children and the usefulness of a defined diagnostic protocol.

The prospective study included children who were referred to a medical center with asymptomatic gross or microscopic hematuria. The study was conducted between May 1979 and May 2002. The childrens’ primary care physicians discovered microscopic hematuria in random urine samples during routine examinations. The diagnosis was confirmed through repeat urinalysis. Hematuria was defined as more than five red blood cells per high power field. The evaluation included a patient and family history, physical examination, and blood pressure measurement. Laboratory tests included complete blood count; urinalysis; serum creatinine and C3 levels; timed urine collection for creatinine clearance; protein and calcium excretions; and renal ultrasonography or intravenous pyelography. Specific criteria were used to determine which children required renal biopsies.

The study group consisted of 342 children evaluated for asymptomatic microscopic hematuria and 228 for asymptomatic gross hematuria. In the microscopic hematuria group, no cause was identified for 274 patients (80 percent). Hypercalciuria without stone disease was the most common cause of microscopic hematuria (16 percent). Four patients in the microscopic group had poststreptococcal glomerulonephritis; all four returned to normal renal function within three months. Four patients in the microscopic group had structural abnormalities. Only two patients in this group met the criteria for renal biopsy.

In the gross hematuria group, no cause was identified for 86 children (38 percent). Hypercalciuria was the most common cause of gross hematuria (22 percent). Ten children in this group had significant structural abnormalities. Fifty-three children met the criteria for and received renal biopsy. The most common biopsy findings were IgA nephropathy (67 percent) and poststreptococcal glomerulonephritis (11 percent).

The authors conclude that children with asymptomatic microscopic hematuria may not need diagnostic evaluations. Follow-up is necessary because, in rare cases, microscopic hematuria is the first sign of occult renal disease. They add that a diagnostic evaluation is warranted in patients with gross hematuria because of the significant number of structural abnormalities found in this group.