Condition guide
Blood in Urine (Hematuria)
Also known as: Hematuria, Haematuria, Gross hematuria, Microhematuria
In brief
Hematuria means blood in the urine. It may be visible (pink, red or cola-coloured urine) or found only on a urine test. It is often caused by infection or stones, but because it can also be the first sign of a bladder or kidney cancer, it should always be evaluated.
Medically reviewed by Dr. Atip Chatsudthipong, MD on
Written by Editorial teamPublished Updated
What is hematuria?
Gross (visible) hematuria is blood you can see — urine may look pink, red or brown, sometimes with clots. Microscopic hematuria is blood detected only when urine is examined under a microscope; the AUA defines it as three or more red blood cells per high-power field on a properly collected sample.
Even a single episode of visible blood that then disappears should be checked. Blood that comes and goes can still be a sign of a significant problem.
What causes blood in the urine?
| Category | Examples |
|---|---|
| Infection | Urinary tract infections, including bladder and kidney infections |
| Stones | Kidney, ureteric or bladder stones |
| Prostate | Benign prostate enlargement (BPH) with fragile blood vessels |
| Cancer | Bladder, kidney, upper urinary tract or prostate cancer |
| Kidney (medical) disease | Inflammation of the kidney filters (glomerulonephritis), often with protein in the urine |
| Other | Recent urological procedures, injury, very strenuous exercise, inherited conditions |
Blood-thinning medicines do not usually cause hematuria on their own, but they can reveal an underlying problem — so blood in the urine still needs investigation if you take them.
Not all red urine is blood
Beetroot, some berries and food dyes, and medicines such as rifampicin or phenazopyridine can colour the urine. Menstrual blood can also contaminate a sample. A urine test distinguishes these from true hematuria.
Who is at higher risk of a serious cause?
- Smoking, current or past — the most important risk factor for bladder cancer
- Age over about 40, and male sex
- Visible (rather than microscopic) blood
- Occupational exposure to certain chemicals, such as aromatic amines in dye, rubber or leather industries
- Previous pelvic radiotherapy or some chemotherapy drugs
How is blood in urine evaluated?
- Urine tests — to confirm red blood cells and check for infection; infection is treated and the urine re-tested
- Blood tests — kidney function
- Imaging — a CT urogram or ultrasound to examine the kidneys and ureters, chosen according to risk
- Cystoscopy — a look inside the bladder with a thin camera, usually a brief outpatient procedure under local anaesthetic gel
The AUA/SUFU microhematuria guideline uses a risk-based approach, so the tests recommended for microscopic blood depend on age, smoking history and other factors. Visible blood generally warrants both imaging and cystoscopy.
When should you seek medical attention?
Go to an emergency department if you:
- Cannot pass urine because of clots
- Pass large amounts of blood, or feel faint or dizzy
- Have blood in the urine with fever, or after an injury
Book a urology appointment promptly for any visible blood in the urine, even if it has stopped, or if a urine test shows microscopic blood.
How Dr. Atip can help
Dr. Atip can arrange the tests you need — urine tests, imaging and, where appropriate, cystoscopy — and explain the findings clearly. If you are visiting Bangkok for a limited time, let the hospital know when booking so tests can be scheduled as close together as possible.
Frequently asked questions
Is blood in urine always serious?
Not always — infections and stones are common causes. However, blood in the urine can be the first sign of bladder or kidney cancer, so it should always be evaluated, even if it happens only once.
Can exercise cause blood in urine?
Very strenuous exercise can occasionally cause temporary blood in the urine. It should clear within a day or two. If it persists or recurs, a medical evaluation is still recommended.
What is a CT urogram?
A CT urogram is a CT scan with contrast dye that shows the kidneys, ureters and bladder in detail. It is commonly used to evaluate visible blood in the urine.
References
This information is for general education and does not replace a consultation with a qualified doctor. If you have severe symptoms, seek emergency care (in Thailand, call 1669). See our medical disclaimer.