Blood in urine (hematuria) is detected on dipstick and reflects the presence of red blood cells, hemoglobin, or myoglobin. True microscopic hematuria is defined as >2–3 RBCs per high-power field, confirmed on repeat urinalysis.

Key distinction—source of bleeding:

• Dysmorphic RBCs: Suggest a glomerular source (e.g., IgA nephropathy, Alport syndrome)

• Nondysmorphic RBCs: Suggest a lower urinary tract source (e.g., stones, infection, malignancy)

Clinical significance:

• Gross hematuria: High-risk finding (>10–25% malignancy risk); warrants urgent evaluation

• Microscopic hematuria: Lower but meaningful risk (0.5–5%, higher in high-risk patients)

For healthy individuals: Confirm dipstick findings with microscopy. Exclude transient causes (exercise, menstruation, recent sexual activity) before pursuing workup.