DiagnosisChronic kidney disease
Chronic kidney disease (CKD) can be diagnosed with blood and urine tests.
In many cases, it's only picked up because a routine blood or urine test indicates that the kidneys may not be working normally.
Who should be tested for CKD?
See your GP if you have persistent symptoms of CKD, such as:
- weight loss or poor appetite
- swollen ankles, feet or hands (oedema)
- shortness of breath
- tiredness
- blood in your urine
- peeing more than usual, particularly at night
They can look for other possible causes and arrange tests if necessary.
But as kidney disease often has no symptoms in the early stages, some people at a higher risk should ideally be tested regularly.
Regular testing is recommended if you have:
- high blood pressure
- diabetes
- acute kidney injury – sudden damage to the kidneys that causes them to stop working properly
- cardiovascular disease – conditions that affect the heart, arteries and veins, such as coronary heart disease or heart failure
- other conditions that can affect the kidneys – such as kidney stones, an enlarged prostate or lupus
- a family history of advanced CKD or an inherited kidney disease
- protein or blood in their urine where there's no known cause
You're also more likely to develop kidney disease if you're black or south Asian.
People taking long-term medications that can affect the kidneys, such as lithium, omeprazole or non-steroidal anti-inflammatory drugs (NSAIDs), should also be tested regularly.
Talk to your GP if you think you may need regular testing for kidney disease.
Tests for CKD
Blood test
The main test for kidney disease is a blood test that's used to work out how well your kidneys are working. The test measures the levels of a waste product called creatinine in your blood.
Using this result, a calculation that takes into account your age, gender and ethnic group is then done to work out how many millilitres of waste your kidneys are able to filter in a minute.
This measurement is known as your estimated glomerular filtration rate (eGFR).
Healthy kidneys should be able to filter more than 90ml/min. You may have kidney disease if your result is lower than this.
Urine tests
Urine tests are also usually carried out to:
- check the levels of substances called albumin and creatinine in your urine – known as the albumin:creatinine ratio, or ACR
- check for blood or protein in your urine
Alongside your eGFR measurement, these tests can help give a more accurate picture of how well your kidneys are working.
Other tests
Sometimes other tests are also used to assess the level of damage to your kidneys.
These may include:
- an ultrasound scan, magnetic resonance imaging (MRI) scan or computerised tomography (CT) scan – to see what the kidneys look like and check whether there are any blockages
- a kidney biopsy – a small sample of kidney tissue is removed using a needle so the cells can be examined under a microscope for signs of damage
Test results and stages of CKD
Your test results can be used to determine how damaged your kidneys are, known as the stage of CKD.
This can help your doctor decide the best treatment for you and determine how often you should have tests to monitor your condition.
Your eGFR result is given as a stage from 1 to 5:
- stage 1 (G1) – a normal eGFR (above 90ml/min), but other tests have detected signs of kidney damage
- stage 2 (G2) – a slightly reduced eGFR (60-89ml/min), with other signs of kidney damage
- stage 3a (G3a) – an eGFR of 45-59ml/min
- stage 3b (G3b) – an eGFR of 30-44ml/min
- stage 4 (G4) – an eGFR of 15-29ml/min
- stage 5 (G5) – an eGFR below 15ml/min, meaning the kidneys have lost almost all of their function
Your ACR result is given as a stage from 1 to 3:
- A1 – an ACR of less than 3mg/mmol
- A2 – an ACR of 3-30mg/mmol
- A3 – an ACR of more than 30mg/mmol
For both eGFR and ACR, a higher stage indicates more severe kidney disease.
Want to know more?
- Advice for new kidney patients
- Kidney Research UK: stages of kidney disease
- The Renal Association: CKD stages