Information for the public
Blood and urine tests are used to find out if you have kidney problems.
A blood test is used to find out how well your kidneys are working (your 'kidney function'). The test is used to estimate how much waste fluid your kidneys can remove from your blood in a minute. The result is called your GFR (or glomerular filtration rate) and this value is roughly the same as your percentage of normal kidney function.
A urine test is used to show how much protein is leaking into your urine. A small amount of leaking is normal, but an increase in the amount (called proteinuria) can be a sign that your kidneys are damaged.
You should be offered these tests if you are at risk of having chronic kidney disease. If your GFR test shows that you may have a problem with your kidneys that was not known about already, the test should be repeated within 2 weeks. Further tests after 3 months will confirm whether you have chronic (long-term) kidney disease.
If there is still some uncertainty, your doctor may offer you a different GFR test that can sometimes help to rule out or confirm kidney disease.
For more about what your test results mean, see After diagnosis.
You should be offered tests for chronic kidney disease if you have any of the following:
high blood pressure
an episode of acute kidney injury (which is a sudden loss of kidney function)
disease of the heart and blood vessels (cardiovascular disease)
kidney stones, other problems with your kidneys called structural renal tract disease, or an enlarged prostate gland
diseases that can affect the whole body, including the kidneys, such as systemic lupus erythematosus
someone in your family with advanced chronic kidney disease or an inherited kidney disease (passed on through their family)
blood in your urine (called haematuria) without a known cause; this might be blood that can be seen or that is discovered in very small amounts by a urine test.
Your doctor should also discuss and agree with you how often you should be checked for chronic kidney disease (see Checking for worsening disease). For most people who are at risk of chronic kidney disease, but have normal test results, this is often less than once a year.
You should be tested at least once a year if you are being prescribed a medication known to cause kidney problems – these include some drugs used to reduce the activity of the immune system (such as cyclosporin or tacrolimus), lithium (which is used to treat bipolar disorder), and drugs called non-steroidal anti-inflammatory drugs or NSAIDs for short (such as ibuprofen).
If you have had acute kidney injury, you should be told that there is an increased risk of developing chronic kidney disease, or of it worsening if you already have chronic kidney disease. You should continue to have tests for chronic kidney disease for at least 2 or 3 years after an acute kidney injury.
See the section on Other NICE guidance for details of our guidance on acute kidney injury, which includes further advice on what should happen after acute kidney injury.