11 possible causes for blood in urine

Dr Roger Henderson
·6-min read
Photo credit: Javier Zayas Photography - Getty Images
Photo credit: Javier Zayas Photography - Getty Images

If you spot blood in your urine it may be alarming, but it is usually nothing serious. However, because blood in your pee could come from anywhere in the urinary tract, it is worth getting it checked out by your doctor to rule out any underlying medical conditions.

Dr Roger Henderson looks at blood in the urine common causes, investigations and possible treatments:

What is haematuria?

Blood in the urine or peeing blood is medically known as haematuria, and can be either visible to the naked eye so you can see it when you pee, or microscopic and cannot be seen. The usual reasons for blood in urine are linked to problems with the kidneys or bladder and it may be painless or painful depending on the cause.

Around half of all people with visible blood in their urine will have an underlying cause identified, but in microscopic haematuria that cannot be seen this falls to around one in 10. Blood in the urine of men can have different causes from blood in the urine of women, and the blood from a period or the vagina can lead to blood being seen in the urine.

It is possible to have blood in your pee and feel completely well. However, one in five people with visible blood in their urine and one in twelve with non-visible blood are subsequently found to have bladder cancer as the cause.

Photo credit: Peter Dazeley - Getty Images
Photo credit: Peter Dazeley - Getty Images

11 causes of blood in urine

The commonest cause of blood in the urine in the UK is a bladder infection (cystitis), especially in women. Other symptoms linked to cystitis include pain and discomfort when passing urine, a need to pee frequently, pain in the lower abdomen and sometimes a high temperature - these are due to the urine infection causing inflammation of the bladder. Treatment is usually a short course of antibiotics and is very effective.

Other possible blood in urine causes include the following:

1. Pyelonephritis

This is where the kidneys themselves become infected, usually as a consequence of a bladder infection that spreads up to the kidneys. Although less common than simple cystitis, the symptoms are usually more severe with pain in the lower abdomen or flanks, and a higher temperature than with cystitis. Treatment is with a longer course of antibiotics than cystitis, and if severe these may need to be given intravenously for a day or two in hospital.

2. Kidney stones

Small stones can sometimes form in either kidney, and often cause no symptoms but if these pass into a ureter (the tubes that carries urine from the kidneys to the bladder) they can cause severe pain in the abdomen and back and haematuria, especially when they are close to being passed out of the body through the urethra of the penis or vagina. The blood can sometimes be visible in the pee, making it look reddish-brown, or may only be picked up when the urine is tested for blood. Most kidney stones pass out of the body themselves and need no specific treatment apart from pain relief as they move from the kidneys, but if they are large or do not pass naturally then specific treatments to break them up or remove them may be required.

3. Urethritis

Urethritis is often (but not always) caused by a sexually transmitted infection, and refers to inflammation of the tube from the bladder to the outside of the body called the urethra. It is usually simply treated with a short course of antibiotics.

4. Bladder or kidney tumours

The majority of people with blood in their urine do not have cancer but the most common early sign of this condition is blood in the urine. The sooner this is diagnosed the better the long-term outlook, and haematuria in the absence of infection normally means that further tests are arranged urgently to rule out a cancer diagnosis. (Children with blood in their pee rarely have cancer – they usually either have a bladder infection or inflammation in their kidneys).

5. Glomerulonephritis

Glomerulonephritis refers to inflammation of the kidneys and is the most common cause of haematuria in children and young adults. There are a number of conditions that may cause this. Most are linked to problems with the body’s own immune system and come with symptoms such as swelling of the legs due to fluid retention and tiredness.

6. Clotting disorders

Any problem that affects the way your blood clots may trigger blood in the urine (such as haemophilia). Drugs that thin the blood such as Warfarin or a DOAC may also cause haematuria if the dose is too high and the blood is too thin.

7. Trauma

Trauma to the kidneys such as after a fall or a punch can cause blood to appear in the urine.

8. Excessive exercise

Extreme exercise, particularly long or ultra-distance running, can cause blood in the urine to appear.

9. Sickle cell disease

Sickle cell disease is a group of inherited red blood cell disorders than can cause a wide range of other problems including kidney or urinary problems and blood in the urine.

10. Polycystic kidney disease

Polycystic kidney disease is a genetic disorder that causes fluid-filled cysts to grow in your kidneys and symptoms can include blood in the urine.

11. Medication

Some medication such as the antibiotics rifampicin and nitrofurantoin, and foods such as beetroot may turn the urine red so it looks as if there is blood in it - when in fact there is not.

What should I do if I see blood in my urine?

Always see your GP as soon as possible as proven blood in the urine – whether visible or not – should always be investigated. Your doctor will take a history, do a physical examination and assess your urine in the surgery to see if infection is present and if further tests may be needed.

Your doctor may start you on antibiotics but if blood is confirmed in your urine in the absence of infection you are likely to be referred for further investigations using the fast-track system in the NHS. This is especially important if any of the following applies:

  • You are over the age of 45 and infection is not present.

  • If the blood fails to clear following treatment for an infection.

  • If microscopic bleeding is present but significant urinary symptoms are present.

  • If microscopic bleeding is present, and you are over the age of 60 with a high white blood count on blood testing, or discomfort when peeing.

Photo credit: anilakkus - Getty Images
Photo credit: anilakkus - Getty Images

Blood in urine investigations

Further blood in urine investigations include an examination of the urine for cancer cells (cytology), X-rays and scans – such as ultrasound and CT scans and intravenous urograms (IVUs), and a flexible cystoscopy which involves putting a small thin telescope into the bladder through the urethra under local anaesthetic and antibiotic cover, allowing a doctor to see inside the bladder.

Blood in urine treatments

Haematuria treatment depends on the cause of the bleeding. If abnormalities are found on testing, your health professional will advise you as to what treatment is necessary and what this involves. Never ignore blood in the urine, even if you have had normal tests for it in the past.

Last updated: 26-04-2021

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