Isolated Hematuria

By Hossein Aliabadi, M.D., F.A.A.P., F.A.C.S.

Table 1
Categories of Causes of Hematuria

Obstructive uropathy

Foreign body

Coagulopathies

Urinary tract infection

Systemic disease

Hypercalciuria

Glomerulonephritides

Anatomic abnormalities

Cystic renal disease

Nephrolithiasis

Benign recurrent

Urolithiasis

Benign familial

Neoplasms

Idiopatnic

Trauma

Drug toxicity

Sepsis

 

While hematuria is common in children, the presence of an abnormal quantity of red cells in the urine of a child nevertheless causes concern to the child, the parents and to the physician. Although the presence of a few red blood cells in the urine is normal, the detection of more than 3 per high-power field in a centrifuge specimen is generally considered abnormal and requires further investigation. It is not uncommon in a busy practice to detect microscopic hematuria on routine urinalysis in a child who otherwise appears perfectly healthy, without any other findings to support a specific cause. Under these circumstances, its cause is often benign and its course limited; nevertheless, an evaluation is necessary to differentiate this form of hematuria from the other more serious but less common disorders.

A well-detailed history, physical examination, and urinalysis are the cornerstones for the evaluation of hematuria, often providing specific diagnostic clue-Standard references tabulate numerous causes for hematuria and discoloration of urine due to various substances, including drugs (Table 1). However, in a significant number of cases, despite best efforts, only isolated microscopic hematuria exists. In such instances, we utilize a diagnostic schema (Figure 1) to help identify the etiology of microscopic hematuria in children. As a member of the team of physicians, pediatric urologists can greatly facilitate the evaluation and management of childhood hematuria in a methodical, cost-effective, and efficient manner, avoiding unnecessary invasive diagnostic procedures.

 

URINALYSIS                    

A thorough microscopic examination of the urinary sediment is paramount. In the office setting, the results of dipstick tests for detection of blood in the urine is usually the first clue. The chemical reaction is based upon the peroxides activity of hemoglobin when it comes in contact with a peroxides substrate contained within the strip of the dipstick. The intensity of color change indicates increasing concentrations of hemoglobin. While the dipstick carries a sensitivity of about 90 percent, microscopic examination of fresh, centrifuged urine is necessary to differentiate true isolated hematuria from other causes for the color change. Abnormal red blood cell morphology and the presence of cell casts are more consistent with renal parenchyma! abnormalities, such as various forms of glomerulonephritis, which would require appropriate urologic and nephrologic assessment. While distorted and irregular red cells can be seen in other conditions such as stone disease or urinary tract infection (UTI), their detection along with casts and proteinuria is a strong indiction for glomerular bleeding. In contrast, the presence of morphologically normal red blood cells requires a thorough urologic evaluation.

Urinary tract infection is the most common urologic cause of hematuria in children. In addition to pyelonephritis, viral or bacterial cystitis can cause gross or microscopic hematuria and we obtain urine cultures in all these patients at the initial evaluation. If red cell casts are present, we also obtain a complete blood count, blood urea-nitrogen, creatinine, total serum proteins with albumin/globulin ratio, in addition to serum complement and antinuclear antibodies, and anti-streptolysin (ASO titer).

IMAGING STUDIES                    

A spot urinary calcium/creatinine ratio is obtained to detect cases of occult hypercalcuria which may be associated with microhematuria without other cellular elements in the urine. Ratios greater than 0.18 in the first morning voided specimen correlates with 24-hour excretion of calcium of 4 mg/Kg/day or more. The possibility of present or future stone disease needs to be considered under these circumstances, with or without detection of crystals in the urine. In such instances, crystaluria (e.g. calcium oxalate, calcium phosphate) may or may not be detected in the urine. In such instances, crystalluria (e.g. calcium oxalate, calcium phosphate) may or may not be detected in the urine. Thus, a well-studied urinalysis suggests the source of hematuria and directs the approporiate blood and urinary imaging studies to be obtained.

We obtain a complete renal and bladder ultrasound with a pre- and post-void imaging to assess renal parenchyma! echo texture, in addition to evaluating the collecting systems. We specifically request pediatric radiologists to pay close attention to the appearance of the bladder wall lining and the bladder neck to avoid overlooking any parenchymal lesions. When properly performed, ultrasonography would appear to be one of the most significant contributions to the evaluation of hematuria in children and we rely on its finding to help us formulate additional studies as necessary. If the examination is not absolutely and convincingly normal, a voiding cystourethrogram and, occasionally, an intravenous pyelogram is obtained. Other imaging studies, including computerized tomography, magnetic resonance imaging (MRI), and/or angiography may need to be obtained depending on each clinical situation, the degree of hematuria, and the results of the preliminary examinations.

CYSTOSCOPY                    

We view cystoscopy in children with isolated microscopic hematuria, in the absence of any demonstrable lesions on the imaging studies of the upper and lower urinary tract, or any urinary tract infection, as unnecessary and of very limited value. In the very few cases in which this modality has been utilized, we have found no added advantage to cystoscopy as a diagnostic tool. However, cystoscopy has proven complementary in cases where the other evaluations have suspected a lesion involving the collecting systems and, if used judiciously, can be provide important information.

CONCLUSION                    

The evaluation of isolated microscopic hematuria in children should be tailored to each individual.  Only in very specific circumstances are invasive evaluations such as cystoscopy required.  Detailed urinalysis, including a carefully performed microscopic examination of the sediment, red cell morphology, urine culture, and detailed history and physical examinations, including blood pressure determinations, are the cornerstones for the evaluation of microhematuria in children.  When properly performed, ultrasonography has been a tremendously helpful addition, and has to a great extent replaced other more invasive and less convenient imaging studies.

 

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