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What is blood in urine?

Blood in the urine (known medically as haematuria) can be an indication that the kidneys aren’t working properly.

It can be caused by a variety of issues, some of them serious, so make an appointment to see your GP if you think you may have blood in your urine.

What does blood in urine look like?

Urine can appear pink, red or even dark brown, like the colour of weak black tea. Sometimes there may only be microscopic quantities of blood, so doctors often use a simple dipstick test (using a sample of urine) to confirm if blood is present.

Causes of blood in urine

There are many possible causes for blood in urine including:

Urinary infection (cystitis)

This is by far the most common cause of haematuria, particularly in young women. It can also be referred to as a urinary tract infection (or UTI). If blood in urine coincides with symptoms of cystitis and disappears a few days after the infection is treated by your GP, no further tests are usually carried out. The other symptoms of cystitis are:

  • burning feeling on passing water
  • feeling the need to pass urine more often
  • feeling that the bladder has not been emptied
  • sometimes a fever and feeling unwell.

Kidney stones

Bleeding may occur when a kidney stone is being passed. This can often be accompanied by an attack of severe pain from the loins (the sides between your lower ribs and pelvis), across the abdomen and into the groin.

Large stones inside the kidney may also cause very slight bleeding. This can usually only be detected by the dipstick test.

Tumours in the bladder or kidney

Bladder and kidney tumours tend to become more common with increasing age, so haematuria in anyone over 40 requires further investigation.

Glomerulonephritis (nephritis)

Glomerulonephritis is a general term for several conditions involving damage to the kidney filters. It is the most common cause of blood in the urine of children and young adults, but it can occur at any age.

Polycystic kidney disease

Polycystic kidney disease (PKD) is an inherited disorder which is present from birth but seldom causes symptoms before adult life. Blood in the urine, sometimes accompanied by pain in the loin, is often the first symptom of the illness.

Blood disorders

Blood clotting abnormalities (e.g. haemophilia, or Warfarin treatment) can cause haematuria, but the haematuria shouldn’t be put down to the blood clotting problem without a check for other causes.

Sickle cell disease

Haematuria can eventually become a feature of sickle cell disease, an inherited condition which mainly affects people from African and Afro Caribbean backgrounds and is usually diagnosed in childhood.

Alport’s disease and thin basement membrane nephropathy

These are diseases in which genetic mutations in genes for a particular type of collagen disrupt the structure of the kidney filters, making it easier for red blood cells to leak through the filters. Some forms are benign, but others can progress. At present, a kidney biopsy (a medical procedure in which a small sample of kidney tissue is taken with a needle and then examined under a microscope) is often necessary to make an accurate diagnosis,

Prostate problems

Diseases of the prostate gland may also cause haematuria in men.

Kidney injury

You may get blood in your urine if you injure your kidneys (e.g. if you are involved in an accident).


Some blood diseases can cause the blood pigment haemoglobin to leak into the urine and turn it red or reddish-brown. This is known as haemoglobinuria. It can also arise as a complication of having an artificial heart valve and can even be brought on by prolonged running on hard surfaces.


Harmless causes of red urine

Urine can also change colour due to:

  • Menstruation – as menstrual blood is discharged at the same time as urine.
  • Food colourings – foods (such as beetroot) and some food dyes can turn urine red.


Resources for you

Haematuria should always be checked out – whatever the cause – so see your GP if you notice blood in your urine.

More information is available from The Edinburgh Renal Unit.

Reviewed April 2019

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Dr Louise Oni
Dr Louise Oni

"The award will allow us to begin to understand how we can tackle the condition early with the vision to stop kidney failure.”

Dr Louise Oni

Researcher spotlight

Immunoglobulin A (IgA) vasculitis (also known as Henoch-Schönlein Purpura) is a disease that causes the immune protein IgA to collect in small blood vessels throughout the body, causing them to become inflamed and leak blood.

Dr Louise Oni from the University of Liverpool has been awarded a paediatric research project grant to investigate whether the levels of certain immune substances can be used to predict which children with IgA vasculitis will go on to develop kidney damage, and whether drugs targeting these immune substances could prevent this. 

Our life-saving research is only possible with your support.

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