Blood in Urine (Hematuria)

What blood in urine looks like

Doctors divide hematuria into two types:

• Gross (visible) hematuria: urine looks pink, red, brown or like cola. It only takes about 1 ml of blood to change the color of a liter of urine, so the amount of blood is often small even when the color is dramatic. Clots may be seen.
• Microscopic hematuria: the urine looks normal, but a dipstick or microscope finds red blood cells. It is usually found during a routine checkup.

The color can hint at the source. Bright red blood or clots usually come from the bladder or prostate. Brown or cola-colored urine suggests blood from the kidneys or muscle breakdown.

Things that turn urine red but are not blood

• foods: beets, blackberries, rhubarb, food dyes
• medicines: rifampin, phenazopyridine (a urinary pain reliever), some laxatives, and the chemotherapy drug doxorubicin
• muscle protein (myoglobin) in rhabdomyolysis, which gives a positive dipstick but no red cells under the microscope
• vaginal bleeding or rectal bleeding mixing with urine

A urine test confirms whether red cells are actually present.

Common causes of blood in urine

Serious causes

• Bladder cancer: the most important cause to rule out. Classically causes painless visible blood that comes and goes. Smoking is the biggest risk factor, along with older age and workplace chemical exposure (dyes, rubber, leather, paint).
• Kidney cancer: blood in urine, sometimes with a side ache or a lump.
• Prostate cancer: less often causes visible blood.
• Glomerulonephritis: inflammation of the kidney's filters, often with protein in the urine, high blood pressure, swelling and brown urine. It can follow a throat or skin infection or come with IgA nephropathy, lupus or vasculitis.
• Polycystic kidney disease, sickle cell disease and trait.

Benign conditions that cause blood in urine

Several harmless or minor conditions explain many cases once serious causes are excluded:

• Exercise-induced hematuria: common in runners, clears within a few days.
• Thin basement membrane disease: an inherited thinning of the kidney filters that causes persistent microscopic hematuria with normal kidney function. It often runs in families and usually needs only monitoring.
• Menstrual contamination of the sample.
• Simple kidney cysts.
• Enlarged prostate with fragile blood vessels.

These are diagnoses made after testing, not assumptions to make at home.

Can blood in urine be temporary?

Yes. Blood from a UTI clears once it is treated, and blood after hard exercise or a procedure usually clears within 1 to 3 days. However, bladder cancer often bleeds on and off, with weeks or months of clear urine between episodes. Blood that goes away by itself is not proof that nothing is wrong. Doctors recommend investigating any episode of visible hematuria, and recheck the urine after an infection is treated to confirm the blood has gone.

Blood in urine in women and men

Women: UTIs are the most common cause. Menstrual blood can contaminate samples, so testing is repeated after a period. Endometriosis rarely involves the bladder and causes cyclical blood in the urine.

Men: an enlarged prostate, prostatitis and prostate procedures are common causes. Because UTIs are less common in men, blood in a man's urine needs fuller investigation.

How doctors investigate hematuria

1. History and examination: pain, urinary symptoms, smoking, occupation, medicines, recent exercise or infection, family history of kidney disease, and blood pressure.
2. Urine tests: dipstick, microscopy to confirm red cells, culture for infection, and protein measurement.
3. Blood tests: kidney function (creatinine), blood count and sometimes PSA in men.
4. Imaging: CT urogram (a CT scan with contrast) or kidney ultrasound to look at the kidneys and ureters.
5. Cystoscopy: a thin camera passed into the bladder under local anesthetic to look for tumors. This is the only reliable way to see small bladder cancers.

The extent of testing for microscopic hematuria depends on your risk: age, sex, smoking history and how much blood is found. If kidney disease is suspected (protein in the urine, abnormal-shaped red cells, high blood pressure), you may be referred to a kidney specialist.

Treatment

Treatment targets the cause:

• antibiotics for infections
• pain relief, fluids and sometimes procedures for kidney stones
• medicines or surgery for an enlarged prostate
• surgery, chemotherapy or immunotherapy for cancers
• blood pressure control and specific treatments for glomerulonephritis

If no cause is found after full investigation, you may be advised to have a repeat urine test, often yearly, and to return if visible blood recurs.

Frequently asked questions

Can blood in urine be temporary?

Yes. It often clears after a UTI is treated, after hard exercise or after a procedure. But bladder cancer can bleed on and off, so visible blood that stops by itself should still be investigated, especially if you are over 40 or smoke.

What benign conditions cause blood in urine?

Harmless causes include exercise-induced hematuria, thin basement membrane disease, menstrual contamination, simple kidney cysts and an enlarged prostate. These are diagnosed after tests have ruled out infection, stones, kidney disease and cancer.

Is blood in urine without pain serious?

It can be. Painless visible blood is the classic sign of bladder cancer, though infection, prostate enlargement and exercise are more common causes. Painless blood should always be checked promptly.

Should I go to the ER for blood in urine?

Go to the ER if you cannot pass urine because of clots, are passing heavy blood with dizziness, have severe side pain with vomiting, or have fever and chills with back pain. Otherwise, see your primary care doctor within a few days.

Can dehydration cause blood in urine?

Dehydration makes urine dark yellow or amber, which can be mistaken for blood, but it does not usually cause bleeding. Severe dehydration can contribute to kidney stones and infections, which can. A urine test tells the difference.