Blood in Urine (Hematuria): Causes and When to Worry

You looked down at the toilet and saw pink, red, or tea-colored urine staring back at you. Your heart skipped a beat. Blood in your urine is alarming - and it should prompt a doctor visit even if you're not in pain.

Hematuria (blood in urine) affects about 2-30% of the population at some point. While many causes are benign - urinary tract infections, kidney stones, vigorous exercise - it can also be the first sign of bladder or kidney cancer. The key distinguishing feature? Painless blood in urine is more concerning than painful blood.

Never ignore blood in your urine. Let's talk about what causes it, when it's an emergency, and why every case deserves medical evaluation.

What It Feels Like

There are two types of hematuria:

Gross hematuria (visible blood):

• Urine is visibly pink, red, brown, or tea-colored
• You can see the blood without a microscope
• May appear at beginning of stream, throughout, or at the end
• Can range from slightly pink to bright red to dark brown
• No change in how much you pee or how it feels (unless underlying condition causes other symptoms)

Microscopic hematuria (invisible blood):

• Urine looks normal to the naked eye
• Blood only detected during urinalysis (routine physical, insurance exam, pre-surgery testing)
• You have no idea there's blood until a test reveals it
• Found in 2-30% of routine urine tests

Key distinction - painful vs. painless:

Painful hematuria (with burning, urgency, frequency, flank pain):

• Usually indicates infection or kidney stone
• Still needs evaluation but less likely to be cancer

Painless hematuria (blood without discomfort):

• More concerning for cancer, especially bladder cancer
• Demands thorough evaluation regardless of age
• Most important warning sign

Color variations:

• Pink or light red: Small amount of blood
• Bright red: Fresh blood, often from bladder or urethra
• Dark red or brown: Older blood, may have been in bladder longer
• Tea or cola colored: Suggests kidney involvement or older blood

Pattern matters:

• Beginning of stream: Often urethral bleeding
• Throughout stream: Usually bladder or kidney source
• End of stream: May indicate bladder neck or prostate issue

Common Causes

Urinary Tract Infection (UTI)

Symptoms: Blood in urine plus burning, frequency, urgency, cloudy or foul-smelling urine, lower abdominal pain.

Why bleeding occurs: Bacteria inflame and irritate bladder lining, causing small blood vessels to bleed.

Treatment: Antibiotics clear infection quickly. Blood should resolve within days.

Most common cause of painful hematuria, especially in women.

Kidney Stones

Symptoms: Blood in urine plus severe flank pain (back/side), pain radiating to groin, nausea/vomiting.

Why bleeding occurs: Sharp-edged stone scrapes urinary tract lining as it moves from kidney to bladder to urethra.

Blood pattern: Often visible, may come and go with pain waves.

Treatment: Small stones pass with hydration and pain management. Larger stones need procedures.

Bladder Cancer

Critical fact: About 80-85% of people with bladder cancer first present with blood in urine. It's the #1 symptom.

Key characteristics:

• Painless gross hematuria (visible blood without discomfort)
• Blood may appear once, disappear, then return weeks/months later
• More common in men (4:1 ratio)
• Risk increases with age (median diagnosis age 73)

Risk factors:

• Smoking (biggest risk - causes 50% of cases)
• Age over 55
• Chemical exposure (aromatic amines in dye, rubber, paint, textile industries)
• Chronic bladder inflammation
• Previous radiation to pelvis
• Family history

Important: Even a single episode of painless visible blood needs cystoscopy (camera in bladder) to rule out cancer.

Kidney Cancer

Hematuria is #1 symptom of kidney cancer (renal cell carcinoma), present in 40-50% of patients at diagnosis.

Characteristics:

• Often painless gross hematuria
• May have flank pain, palpable mass, weight loss, fever
• More common in men (2:1 ratio)
• Peak incidence ages 60-70

Risk factors:

• Smoking
• Obesity
• Hypertension
• Family history
• Certain genetic conditions (Von Hippel-Lindau disease)

Enlarged Prostate (BPH - Men)

Common in men over 50. Enlarged prostate has fragile blood vessels on its surface that bleed easily.

Symptoms: Blood in urine plus weak stream, difficulty starting, frequent urination (especially at night), feeling of incomplete emptying.

Usually benign but needs evaluation to rule out prostate cancer.

Kidney Disease

Glomerulonephritis (inflammation of kidney's filtering units) can cause blood in urine.

Symptoms: Brown or cola-colored urine, high blood pressure, swelling in face/hands/feet, foamy urine (protein).

Causes: Post-infection (strep throat), autoimmune disease, vasculitis.

Serious: Can progress to kidney failure if not treated.

Vigorous Exercise

"Runner's hematuria" - occurs after intense exercise, especially running.

Why it happens:

• Bladder trauma from repeated bouncing
• Dehydration concentrating urine
• Breakdown of red blood cells from foot-strike impact
• Reduced blood flow to kidneys during intense exercise

Characteristics: Temporary, resolves with rest and hydration within 24-72 hours.

Diagnosis of exclusion: Must rule out serious causes first. Don't assume exercise is the cause without medical evaluation.

Other Causes

Medications:

• Blood thinners (warfarin, aspirin, clopidogrel)
• Cyclophosphamide (chemotherapy)
• Penicillin
• Rifampin (antibiotic that makes urine orange-red)

Inherited conditions:

• Sickle cell disease
• Alport syndrome
• Polycystic kidney disease

Trauma:

• Injury to kidneys, bladder, or urethra
• Catheterization
• Recent procedure on urinary tract

Menstruation contamination:

• Women may see blood during period - not true hematuria

When to See a Doctor

See a doctor promptly (within days) for:

• Any visible blood in urine (even one episode)
• Microscopic blood detected on routine testing
• Blood with any urinary symptoms

Every case of hematuria needs evaluation. Don't wait to see if it goes away.

Who's at Highest Risk for Cancer

Bladder cancer red flags:

• Age 35+ with painless visible blood in urine
• Current or former smoker
• Male (4x higher risk than women)
• Occupational chemical exposure
• History of pelvic radiation

Kidney cancer red flags:

• Age 50+ with painless blood in urine
• Smoker or former smoker
• Obese
• High blood pressure
• Family history of kidney cancer

For these high-risk groups, thorough workup including cystoscopy and imaging is essential even for single episode of microscopic hematuria.

Diagnosis

Your doctor will conduct thorough evaluation to identify the cause:

Medical history and physical exam:

• Symptom timeline
• Pain characteristics
• Recent infections, exercise, medications
• Smoking history, occupational exposures
• Family history of kidney disease or cancer

Urinalysis: First test - confirms blood, checks for infection, protein, cancer cells.

Urine culture: Identifies bacteria if infection suspected.

Urine cytology: Examines urine under microscope for cancer cells. Not very sensitive but highly specific for bladder cancer.

Blood tests:

• Kidney function (creatinine, BUN)
• PSA (prostate-specific antigen) in men over 50
• Complete blood count

Imaging:

CT urogram (most comprehensive):

• CT scan with IV contrast that highlights urinary system
• Shows kidneys, ureters, bladder in detail
• Detects stones, tumors, structural abnormalities
• Gold standard for evaluating hematuria

Ultrasound:

• Non-radiation option
• Good for detecting kidney masses
• Less sensitive than CT for small lesions

Cystoscopy (critical for bladder evaluation):

• Camera inserted through urethra into bladder
• Directly visualizes bladder lining
• Detects bladder tumors, stones, inflammation
• Can biopsy suspicious areas
• Essential for evaluating painless hematuria in adults

Treatment

Treatment depends entirely on the underlying cause:

For UTI:

• Antibiotics (nitrofurantoin, trimethoprim/sulfamethoxazole)
• Symptoms improve within 1-2 days
• Blood should clear shortly after

For kidney stones:

• Pain management (NSAIDs work well)
• Hydration
• Medications to help stone pass (alpha blockers)
• Procedures for larger stones (ESWL, ureteroscopy)

For bladder cancer:

• Early stage: TURBT (transurethral resection), intravesical chemotherapy or immunotherapy
• Advanced: Radical cystectomy (bladder removal), chemotherapy, immunotherapy
• Prognosis: 5-year survival 77% overall, 96% for localized disease

For kidney cancer:

• Localized: Partial or radical nephrectomy (kidney removal)
• Metastatic: Targeted therapy, immunotherapy
• Prognosis: 5-year survival 77% overall, 93% for localized disease

For enlarged prostate:

• Medications (alpha blockers, 5-alpha reductase inhibitors)
• Minimally invasive procedures
• Surgery for severe cases

For kidney disease:

• Treat underlying cause
• Blood pressure control
• Reduce protein in diet
• Immunosuppressants if autoimmune

For exercise-induced hematuria:

• Rest and hydration
• Reduce exercise intensity
• Stay well-hydrated during exercise
• Consider different activities if recurrent

Prevention

You can't prevent all causes of hematuria, but you can reduce risk:

Stop smoking: Single most important preventive measure for bladder and kidney cancer.

Stay hydrated: Reduces risk of kidney stones and UTIs. Dilutes urine and flushes bacteria.

Limit chemical exposure: If you work with dyes, rubber, paint, or textile chemicals, use protective equipment.

Urinate after sex: Reduces UTI risk (common cause of painful hematuria).

Healthy weight: Reduces kidney cancer risk.

Treat high blood pressure: Protects kidney function.

Respond to urinary symptoms promptly: Don't ignore burning, frequency, or urgency. Early treatment of UTIs prevents complications.

The Bottom Line

Blood in urine is never normal. Even a single episode demands medical evaluation. While many causes are benign and treatable (UTI, kidney stones), hematuria can be the first and only symptom of bladder or kidney cancer.

Painless visible blood is the most concerning pattern, especially in adults over 35, smokers, or those with occupational chemical exposure. These cases require thorough workup including cystoscopy and imaging.

Don't ignore blood in your urine hoping it will go away. Don't assume it's from exercise, food, or medication without proper evaluation. Early detection of cancer dramatically improves outcomes - bladder cancer caught early has a 96% five-year survival rate.

See your doctor promptly. A few tests now could save your life.

References

1. American Urological Association - Asymptomatic Microhematuria (2020 AUA Guideline)
2. Cleveland Clinic - Hematuria (Blood in Urine): Causes, Symptoms & Treatment
3. Mayo Clinic - Blood in urine (hematuria) symptoms and causes
4. NCBI StatPearls - Hematuria medical overview
5. National Kidney Foundation - Hematuria in Adults
6. American Cancer Society - Bladder Cancer Early Detection, Diagnosis, and Staging