Categorizing patients with hematuria into one of the following groups is helpful:
· Gross hematuria
o Gross hematuria is alarming for the child's parents and sometimes for their pediatricians.
o Gross hematuria is an uncommon finding in an unselected population of children. The prevalence of gross hematuria was reported as 0.13%, based on a retrospective review of children seen in an emergency walk-in clinic.
o Most children with gross hematuria (56%) have an easily recognizable and apparent cause. The most common diagnoses include urinary tract infection, perineal irritation, trauma, meatal stenosis with ulceration, coagulation abnormalities, and urinary tract stones.
o Less than half (44%) of children with gross hematuria had a cause that was either not obvious or that required additional or more sophisticated examinations. Among the diagnoses in this group are recurrent gross hematuria, acute nephritis, ureteropelvic junction obstruction, cystitis cystica, epididymitis, tumor, hyperuricosuria, and hypercalciuria.
o These children require referral to a pediatric nephrologist for detailed investigation and management.
· Microscopic hematuria with clinical symptoms
o A child who presents with either symptoms of an illness or a physical abnormality and is discovered to have concurrent microscopic hematuria should be placed in this category.
o Some of the clinical conditions with associated renal involvement that may be recognized by the primary physician are acute glomerulonephritis, acute interstitial nephritis, urinary tract infections, familial hematuria (both benign recurrent and progressive hereditary nephritis), Henoch-Schönlein purpura, systemic lupus erythematosus, hypertension, hypercalciuria, and urolithiasis.
o Unless the patient falls into a clear category of illness that is easily identified, an early consultation with the pediatric nephrologist should be obtained, because most other illnesses require additional expertise in either delineation or management.
o The child with microscopic hematuria associated with clinical symptoms may have a vast number of diseases or conditions, which makes this a difficult category for which to suggest specific evaluation.
o The first step in this category is to direct the evaluation based on the symptoms or physical examination findings. The extent and thoroughness of the evaluation depends on the knowledge and experience of the physician.
o The child with a complicated diagnosis or unexplained cause for the hematuria should be referred to a pediatric nephrologist or, in some cases, to an appropriate subspecialist. If a diagnosis is straightforward, the appropriate therapy or follow-up is administered.
o If the child has recurrence of the symptoms and associated hematuria or if the hematuria is persistent, referral to a pediatric nephrologist is recommended.
· Asymptomatic microscopic hematuria with proteinuria
o In the asymptomatic child, simultaneous microscopic hematuria and proteinuria (>50 mg/dL) in 3 consecutive urine samples is unusual and occurred in the Galveston study, with a prevalence of 64 per 100,000 school children (approximately 0.06%). All of the children in this survey who were thought to have significant renal disease were included in this group. Despite the obvious concern attendant to this combined finding, almost 50% of the children who were discovered to have both hematuria and proteinuria had spontaneous resolution of both findings during the course of the 5-year follow-up.
o The significance of the renal involvement, in most cases, correlates directly with the quantity of protein being excreted. Thus, the combination of asymptomatic microscopic hematuria and proteinuria seems to suggest that such patients are more likely to have significant renal disease.
o The first step in this category is to quantitate the urine protein at the initial or follow-up visit. Asymptomatic patients who are found to have both hematuria and proteinuria in several samples collected over a few weeks should be referred to a pediatric nephrologist for further evaluation and recommendations.
· Asymptomatic microscopic (isolated) hematuria
o Asymptomatic microscopic hematuria is common in unselected populations of children. The discovery of hematuria alone in an asymptomatic child is merely an indication for repeat testing on one or more occasions.
o The Galveston County epidemiology study found that, of children who had 3 consecutive urine samples that demonstrated hematuria, only 37% had hematuria 1 year later. Thus, the cause for the asymptomatic hematuria had apparently resolved in 63% of the children over the course of a single year. Significant renal disease was almost nonexistent in patients in whom hematuria was the only abnormality found.
o In cases involving the development of proteinuria or pyuria, the condition of isolated asymptomatic hematuria is no longer observed, and other studies should be performed. If the microscopic hematuria persists unchanged for more than 1-2 years, a few additional studies may be indicated.
o One possible entity responsible for such an asymptomatic persistence of hematuria is idiopathic hypercalciuria or hyperuricosuria.
o Familial or hereditary hematuria, whether benign, nonprogressive (ie, "thin basement membrane disease"), or progressive (ie, Alport syndrome or one of its variants), is another condition in which, early in the course, hematuria may be found in the absence of proteinuria.
o IgA nephropathy may also present with microhematuria.