Description

• Hematuria is defined as ≥3 to 5 RBCs per high-power field (HPF) using a standard urinalysis technique on a centrifuged sample.
• Persistent hematuria: hematuria on >2 separate examinations
• Macroscopic or gross hematuria: hematuria visible to the naked eye
• Microscopic hematuria: hematuria detected by urinalysis or microscopy only

Epidemiology

• Prevalence of asymptomatic microscopic hematuria in school-aged children is 3–6% on single urine sample and ≤1% on two or more urine samples.
• Gross hematuria: 0.13% children in walk-in clinic
• Gross hematuria is more common in boys.

Risk Factors

Nephrogenic causes of hematuria, hypercalciuria, nephrolithiasis, and nephritis can be inherited.

Pathophysiology

Hematuria can occur from anywhere along the urinary tract or kidney. Causes of hematuria can be divided into glomerular and nonglomerular causes. In glomerular hematuria, RBCs cross the glomerular basement membrane (GBM) into the urinary space. Urine with dysmorphic red cells, proteinuria, and urinary casts suggest a glomerular origin.