Hematuria in children is defined as greater than 5 red blood cells per high-power field (RBCs/hpf) in the urine on microscopic examination. Most children with hematuria have a benign condition that requires no intervention and that has an excellent prognosis. The incidence of significant disease is low (1% to 7%) with random screening. Since the finding of isolated microscopic hematuria is frequently transient, we recommend documentation on at least 2 of 3 consecutive urinalyses a few weeks apart before pursuing further workup. Hematuria may be microscopic (typically found in asymptomatic children discovered by routine dipstick screening of urine) or macroscopic, also called gross (apparent to the eye as a bright red or brownish discoloration of the urine). When positive, urine dipstick reagents change color and are indicative of the presence of RBCs (at least 5 RBCs/hpf), hemoglobin, or myoglobin. To distinguish among them, microscopic examination should be performed on a properly centrifuged, freshly obtained urine specimen (10 mL of urine spun at 3000 rpm for 5 minutes) to confirm the presence of RBCs, before the diagnosis of hematuria is made. Diagnostic studies should be reserved for those patients who by history, physical examination, and initial laboratory screening tests are deemed to be at high risk for serious renal or urologic disease. Greater than 40% of the time, children with gross hematuria have no identifiable cause. The most common cause of non-glomerular gross hematuria is urinary tract infection (UTI), hypercalciuria, or stones. Around 15% to 20% of patients with painless micro- or macroscopic hematuria have hypercalciuria. Extensive and invasive random laboratory investigations in a child with isolated hematuria are unnecessary and discouraged. The most common cause of glomerular gross hematuria in children is acute postinfectious glomerulonephritis from streptococcal infection of the throat or skin. The presence of proteinuria may warrant diagnostic workup and coordination with a pediatric renal specialist. Causes of hematuria in children are listed in Table 19-1.
In addition to determining the type, duration, and the pattern of the hematuria, a complete history of previous illnesses and associated genitourinary symptoms, medication use, and activity are essential in the workup of a child. One needs to differentiate between surgical and medical etiologies of the hematuria. There are a number of clues in the history that help to better define the etiology of the disease. Important historical and familial features, and the possible corresponding diseases are listed in Table 19-2.
1. Blood pressure should be measured in all children regardless of age, using an appropriately sized cuff.
2. Growth parameters should be plotted on standardized growth charts.
3. Assessment of patient’s skin for rash, petechiae, purpura, pallor, or edema should be done.
4. Abdominal examination should evaluate for palpable masses, signs of trauma, and localization of pain or tenderness.
5. Assessment of external genitalia for signs of inflammation, trauma, or the presence of a foreign body should be carried out.
Distinguishing features on examination and the corresponding diseases are listed in Table 19-3.
Once the diagnosis of hematuria is confirmed on at least two separate occasions over a 2- to 3-week period, a complete urinalysis should be obtained in each patient. Macroscopic or gross hematuria is classically associated with hematuria of glomerular origin. Color is important to evaluate. A red color without RBCs that is heme positive is due to myoglobinuria or hemoglobinuria. It takes one 1 ml of blood/liter of urine to induce a visible color change. Some medications like phenazopyridine and beetroot can also turn the urine red. In cases of brownish, “tea-colored,” or “Coca-Cola colored” hematuria glomerular disease can be considered, which is also supported by the additional findings of proteinuria, hypertension, edema, or azotemia. In contrast, macroscopic hematuria of extrarenal origin is bright red and frequently associated with pain and blood clots.
TABLE 19-2 Historical Features and Associated Diseases
Urinary frequency, dysuria, suprapubic, costovertebral or flank pain
Renal disease (insufficiency, dialysis, or transplantation)
Polycystic kidney disease
Sickle cell disease
Sickle cell nephropathy
The examination of urinary RBC morphology by microscopy can be helpful in determining the site of origin, that is, glomerular versus non-glomerular. As RBCs pass through small disruptions in the glomerular capillary wall due to glomerular disease, RBCs become dysmorphic with distorted and irregular contours, and this is consistent with glomerular disease. Although phase contrast microscopy is the traditional method for examining RBC morphology in urine specimens, many clinicians can evaluate the morphology on routine microscopy. RBCs with normal morphology represent hematuria from trauma, cystitis, and lower urinary tract malignancies. The finding of urinary RBC casts is diagnostic of glomerular disease and is not seen with extrarenal bleeding. Mild proteinuria from the release of hemoglobin from RBCs may be found in all types of hematuria.