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Haematuria is blood in the urine. Sometimes the blood can be seen, but often it is only present in very small amounts and is invisible to the naked eye. A simple test of the urine can detect these very small amounts of blood, and this is one of the checks done at many routine medical examinations.


The main causes of blood in the urine are:-

  1. Infection
  2. Kidney stones
  3. Tumours in the bladder or kidney
  4. Harmless leakage from the bladder area
  5. Glomerulonephritis

The initial assessment in someone with haematuria is to determine the following:-

  1. Is there any infection (eg pain passing urine)
  2. Is blood in the urine visible to the naked eye?
  3. What is the level of protein in the urine?
  4. What is the overall function of the kidneys (blood creatinine level or eGFR)

The most important thing to check is whether someone with haematuria has a kidney or bladder cancer. Even if someone has longstanding kidney disease, new onset haematuria should be checked to make sure there is no cancer present. If someone has been checked to rule out cancer and keeps on getting blood in the urine, they should discuss with their medical team whether ongoing tests are needed. If blood in the urine is not visible to the naked eye, a glomerulonephritis may be suspected, especially if there is also protein in the urine and the kidney function is reduced. Referral to a kidney specialist (nephrologist) may be needed if glomerulonephritis is suspected and the kidney function is reduced.


Glomerulonephritis (or nephritis for short) is inflammation in the kidney caused by activity of the immune system. White blood cells or antibodies are present in the body to fight infection and can sometimes damage the kidney by mistake. This damage to the kidney can only be seen under the microscope and is often very minor.


There are many different types of glomerulonephritis, and the outcome depends upon which type is present. In general, nephritis will either:-

  1. Occasionally go away on its own
  2. Often stay the same for many years without causing trouble
  3. Occasionally lead to high blood pressure or kidney failure

The likelihood of running into trouble from the glomerulonephritis depends on the type of glomerulonephritis that is present. Although a lot of blood will be taken for various tests, these do not usually give a definite diagnosis. A kidney biopsy generally provides a lot of information but is not without risks.


Doctors can tell what is going on in the kidney by removing a small fragment with a needle and looking at it under the microscope (this is called a kidney biopsy). The procedure to take the biopsy takes about 20 minutes and the sample is taken using a needle, not open surgery. In terms of discomfort, most people report it is about the same as a visit to the dentist.

Doctors are always cautious about recommending a kidney biopsy because there is a small risk of bleeding afterwards. The risk of serious bleeding is less than 1 in 1500 for someone with normal sized kidneys, normal blood pressure and normal kidney function. To minimise the risk of bleeding, the blood is checked in the laboratory to make sure it clots properly, and you will be rested in bed after a biopsy. If you have a past history of unusual bleeding after operations or dental extractions, you should tell us before the biopsy. Vigorous activity should not be performed for up to 2 weeks after a biopsy, or longer if there are any problems.


How strongly your specialist recommends a kidney biopsy depends upon the details of your case and will be discussed in detail with you. If you do not want a biopsy, obviously no-one will be 100% sure what is wrong with you. Since there is no cure for many types of nephritis, this sometimes does not matter too much. If you do not have a biopsy, doctors would have to treat you as though you had one of the more serious types of nephritis, with regular blood pressure checks and measurement of the kidney function.


The answer is usually yes. Glomerulonephritis only rarely causes pain over the kidneys, and most people have no symptoms. The loss of blood is not enough to cause anaemia. The presence of a minor glomerulonephritis should not place any restrictions on employment, family life, or other aspects of normal life.

You will probably have to mention the condition when applying for life insurance or a mortgage, however, unless there is kidney failure or another serious problem, there should not be any major difficulties with the application. It may be necessary for your specialist to give a medical report, though. 

Last reviewed July 2022
Next review July 2025

Reviewed by Dr Oshini Shivakumar 'Specialist Renal Registrar'

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The National Kidney Federation cannot accept responsibility for information provided. The above is for guidance only. Patients are advised to seek further information from their own doctor.