Kidney disease stages
The term chronic kidney disease (CKD) is used worldwide to mean any form of kidney disease that goes on for more than a few months.
The word 'chronic' doesn’t necessarily mean 'serious' and the word 'disease' includes any abnormality of kidney structure or function, whether or not it is likely to cause a person to feel unwell or to develop complications.
There are various stages of chronic kidney disease (CKD), ranging from mild loss of kidney function to complete kidney failure, but not all CKD conditions progress to the most serious stage. Most people fall into the mild to moderate categories where hospital-based care is not necessary.
How many stages of chronic kidney disease (CKD) are there?
Explaining chronic kidney disease (CKD) stages
This chart shows the stages of kidney disease and outlines how disease is likely to progress if kidney function reduces and urine protein levels increase.
Reviewed April 2022
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How is kidney disease measured?
Kidney disease is measured and categorised using a blood test which gauges the estimated glomerular filtration rate (eGFR) and a urine test which shows the urine albumin:creatinine ratio (uACR).
If you have CKD your doctor should regularly test your urine and blood to find out if there is any kidney damage, how serious the condition is, whether it is getting worse and what treatments you might need to manage your symptoms.
Glomerular filtration rate: GFR and eGFR
The kidneys have an important role in the body – they filter waste and toxins from the blood, help to maintain the correct water balance and regulate blood pressure. They also return certain minerals back into the blood stream and produce essential hormones.
The estimated glomerular filtration rate, or eGFR, is a measurement calculated from blood test results that helps doctors to understand how well your kidneys are working and identify if you have kidney disease (CKD).
Healthy kidneys typically filter more than 90 ml each minute (this figure is adjusted for body size). A lower rate may indicate chronic kidney disease (CKD).
Albuminuria: the urine albumin:creatinine ratio
A simple urine test called the urine Albumin:Creatinine ratio (ACR) is also performed to look for signs that protein is leaking into the urine (a condition called albuminuria or proteinuria). This is an important sign of kidney damage. The ACR is used to calculate the ‘A stage’ of CKD (as indicated in the stages of chronic kidney disease (CKD) chart below).
There are three recognised stages of albuminuria:
- A1 – normal to mildly increased urine protein levels (lower than 3mg/mmol)
- A2 – moderately increased urine protein levels (between 3-30mg/mmol)
- A3 – severely increased urine protein levels (higher than 30mg/mmol)
Combining your ACR with your eGFR can help doctors try to predict whether your kidney disease is likely to progress and whether you are more likely to develop complications such as heart and circulatory problems. Other factors are also taken into account, e.g. age. In general, the higher the ‘A’ stage, the more likely it is that you will benefit from blood pressure-lowering treatment.
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