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Evaluation of microscopic hematuria in children

Olivia Gillion Boyer, MD, PhD
Section Editors
Patrick Niaudet, MD
Jan E Drutz, MD
Deputy Editor
Melanie S Kim, MD


Microscopic hematuria is a common finding in children. There is a long list of causes of microscopic hematuria, most of which are benign, especially in children with isolated asymptomatic microscopic hematuria. The challenge that faces the clinician is to identify the child in whom hematuria is caused by significant underlying disease and avoid unnecessary testing in those individuals with a benign condition.

The etiology and evaluation of microscopic hematuria in children will be reviewed here. The evaluation of children with gross hematuria is discussed separately. (See "Evaluation of gross hematuria in children".)


Hematuria is defined by the presence of an increased number of red blood cells (RBCs) in the urine. Hematuria can either be visible to the naked eye (gross) or apparent only upon urinalysis (microscopic). Microscopic hematuria may be discovered as an incidental finding on an urinalysis prompted by urinary or other symptoms.

Urinary dipstick — The most common screening test for hematuria is the urinary dipstick test for blood. Dipsticks for hemoglobin are as sensitive as the urine sediment examination, but result in more false-positive tests. In comparison, false-negative dipstick tests are unusual; as a result, a negative dipstick reliably excludes abnormal hematuria.

The reagent strip that detects blood utilizes hydrogen peroxide, which catalyzes a chemical reaction between hemoglobin (or myoglobin) and the chromogen tetramethylbenzidine. Different shades of blue-green are produced according to the concentration of hemoglobin in the urine sample. These strips can detect 5 to 10 intact RBCs/microL, which roughly corresponds to a finding on microscopic examination of two to five RBCs per high-power field from the sediment of a centrifuged 10 to 15 mL urine sample.

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Literature review current through: Nov 2017. | This topic last updated: Aug 19, 2016.
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