Causes
Blood can enter the urine anywhere along the urinary tract, from the kidneys to the urethra:- Urinary tract infections: Bladder and kidney infections inflame the urinary lining, often with burning and urgency.
- Kidney stones: Stones scrape the urinary tract as they form or pass, classically with severe, cramping flank pain.
- Enlarged prostate: In older men, benign prostatic hyperplasia is a frequent source of both visible and microscopic blood.
- Kidney disease: Inflammation of the kidney's filtering units (glomerulonephritis) can leak blood and protein into the urine, sometimes after an infection.
- Vigorous exercise: Long-distance running can cause temporary, harmless hematuria that clears within days.
- Recent procedures or injury: A urinary catheter, a recent prostate or bladder procedure, or a direct blow to the flank can all cause short-lived bleeding.
- Cancers: Tumors of the bladder, kidney, or prostate can bleed - painless visible blood in an older adult, especially a current or former smoker, is the classic warning sign.
Symptoms
Hematuria itself may be the only finding, and visible blood is often painless. Accompanying symptoms help point to the cause: burning and frequency suggest infection; severe one-sided flank pain suggests a stone; a weak stream and nighttime urination in a man suggests prostate enlargement; and swelling with foamy urine points toward a kidney (glomerular) cause. It is also worth knowing that beets, blackberries, certain food dyes, and some medications can turn urine red without any blood at all - a urine test settles the question.Diagnosis
Evaluation begins with a urinalysis and microscopic examination to confirm true red blood cells, plus a urine culture to check for infection. Depending on your age, risk factors, and findings, your physician may order blood tests of kidney function, a CT scan of the urinary tract, and referral to a urologist for cystoscopy - a thin, flexible camera examination of the bladder that is the definitive way to inspect its lining. Microscopic hematuria found on a routine test is typically confirmed on a repeat sample before a larger workup begins.Treatment
Treatment targets the cause, not the blood itself: antibiotics for infection, stone management, treatment of prostate enlargement, or specialist care for kidney disease and tumors. When a thorough evaluation finds no cause - a common and reassuring outcome - your physician may simply recheck a urine sample and your blood pressure periodically.When to Seek Immediate Care
Call your physician the same day, or go to an emergency department, if blood in the urine comes with:- Clots or trouble urinating: Clots can block the bladder outlet and cause painful urinary retention.
- Fever, chills, or flank pain with nausea: These point toward a kidney infection needing prompt treatment.
- Lightheadedness or a racing heartbeat: Heavier or ongoing blood loss should be assessed urgently.
- Severe, unrelenting one-sided flank pain: Often an obstructing stone, which may need urgent intervention.