Hematuria, the presence of blood in the urine, often causes significant alarm for parents. While seeing red or brown urine can be frightening, the cause in children is frequently benign and resolves without intensive treatment. This article clarifies when a child’s hematuria warrants immediate medical attention and when it requires only routine follow-up.
Defining Hematuria and Identifying the Source
Hematuria is classified into two categories based on visibility. Gross hematuria is visible to the naked eye, causing the urine to appear pink, red, brown, or the color of tea or cola. Only a minimal amount of blood, sometimes as little as one milliliter, is sufficient to discolor the entire volume of urine.
Microscopic hematuria is detectable only through laboratory analysis, typically via a urinalysis that reveals an abnormal number of red blood cells. The visibility of blood does not correlate with the severity of the underlying cause. Before confirming true hematuria, a provider must rule out pseudo-hematuria, which is red-colored urine that does not contain red blood cells. Common culprits include certain food dyes, specific medications, and foods like beets or rhubarb, which temporarily alter urine color.
Common and Transient Causes
Common causes of hematuria in children are typically temporary and not indicative of long-term health concerns. One common benign cause is exercise-induced hematuria, which occurs after intense physical activity, particularly in distance runners. This is thought to be caused by temporary changes in kidney blood flow or minor trauma to the bladder walls.
A simple urinary tract infection (UTI) is another transient cause, irritating the urinary tract lining and leading to bleeding. UTIs often present with symptoms like mild pain or a burning sensation during urination, along with increased frequency. Hematuria can also appear briefly during a transient viral illness or fever, related to temporary changes in the kidney’s filtering system.
Mild dehydration, which concentrates the urine and irritates the urinary lining, may contribute to a brief episode of red urine. Hypercalciuria, or high calcium levels in the urine, can also cause recurrent microscopic or gross hematuria. While hypercalciuria requires management to prevent kidney stones, the associated hematuria is generally non-threatening in the short term.
Urgent Warning Signs Requiring Immediate Attention
The presence of accompanying symptoms elevates hematuria to a potential medical emergency requiring immediate consultation. Severe abdominal or flank pain alongside blood in the urine suggests an acute obstruction, such as a kidney stone passing through the ureter. This severe pain indicates a potentially blocked flow of urine.
High fever and vomiting combined with hematuria can signify a severe upper urinary tract infection, such as pyelonephritis, or a rapidly progressing systemic illness. Another serious sign is edema, or sudden swelling, particularly around the eyes or in the extremities. Edema, especially when accompanied by decreased urination, can point toward acute kidney inflammation (glomerulonephritis), which impairs the kidney’s ability to filter waste and fluid.
A history of recent significant trauma to the abdomen or back necessitates an immediate emergency evaluation to rule out a kidney laceration or rupture. The passage of blood clots or a complete inability to urinate (anuria) are critical warning signs. Both clots, which can block the urethra, and anuria, which indicates sudden failure of urine output, require immediate intervention.
Underlying Conditions Requiring Evaluation and Management
Persistent or recurrent hematuria, especially when accompanied by other systemic findings, often indicates an underlying condition requiring specialist evaluation. One significant group of diseases is glomerulonephritis, which involves inflammation of the kidney’s filtering units. This is often suggested by the presence of hematuria, protein in the urine, and high blood pressure.
Specific types include IgA nephropathy, which causes recurrent gross hematuria, sometimes following an upper respiratory infection. Post-streptococcal glomerulonephritis typically occurs one to three weeks after a strep throat infection. Less common are inherited conditions like Alport syndrome or Thin Basement Membrane Disease, which may be suggested by a family history of kidney failure or associated findings like hearing loss.
Structural anomalies of the urinary tract (CAKUT) may also cause recurrent hematuria. The diagnostic workup typically involves blood tests, urine protein-to-creatinine ratio measurements, and imaging studies like a renal ultrasound. This evaluation helps a pediatric nephrologist determine the precise source of the bleeding and formulate a long-term management plan.