Chronic kidney disease (CKD) is divided into five stages by eGFR, from G1 (normal filtration, but signs of damage) to G5 (kidney failure, eGFR below 15). Stage 3 is split into 3a and 3b. You also get an albumin category from A1 to A3, and together they show how high your risk is.
By the Nyrami editorial teamPublished 1 October 2026Updated 2 October 20266 min read
Your test result or medical record may say something like “CKD G3a A2”. It is a code that says how well your kidneys filter, and how much albumin leaks into your urine. Here we explain what the letters and numbers mean, and what they mean for you. To read about the disease itself, its causes and treatment, see Chronic kidney disease.
Chronic kidney disease has five stages, G1 to G5, and stage 3 is split into 3a and 3b. The stage is set by eGFR, which shows how much blood the kidneys clean per minute. The classification comes from the international KDIGO guideline and is used by Norwegian doctors. “Grade” and “stage” mean the same thing.
eGFR (estimated glomerular filtration rate) is calculated from creatinine in the blood, age and sex. If you have a creatinine result, you can work out your eGFR in the calculator. The stage is only set once the value has been at that level for at least three months, because a single test can vary. Read more about the numbers in eGFR: normal range and Creatinine: normal range.
Stages by eGFR (G1 to G5)
G1
G2
G3a
G3b
G4
G5
A1, A2 and A3 show how much albumin leaks into the urine, measured as the albumin to creatinine ratio (uACR, called u-AKR in Norway). A1 is below 3 mg/mmol, A2 is 3 to 30 mg/mmol and A3 is above 30 mg/mmol. The more albumin, the higher the risk that the kidney disease will progress, and the risk of cardiovascular disease.
Albumin is a protein that healthy kidneys hold back. Albumin in the urine is often the very first sign of kidney damage, long before eGFR falls. That is why you can have chronic kidney disease even with a normal eGFR. Read more in Protein in urine.
Albumin categories (A1 to A3)
A1
A2
A3
The risk chart combines stage and albumin category. Green means low risk, yellow moderately increased, orange high and red very high risk. Two people with the same eGFR can therefore have very different risks: the one with a lot of albumin in the urine needs closer follow up and often more treatment.
Risk by stage and albumin (KDIGO)
G1
G2
G3a
G3b
G4
G5
Kidney disease is considered serious when eGFR is below 30 (stages 4 and 5), when a lot of albumin leaks into the urine (A3), or when eGFR falls quickly from year to year. A kidney specialist should then be part of your follow up, and in time the conversation about dialysis, a new kidney or treatment without dialysis begins.
The Norwegian guideline for GPs says that your GP should contact a kidney specialist in stage 5, and in stage 4 with a lot of albumin in the urine. Contact with a kidney specialist is also considered in stage 4 otherwise, in stage 3b, with a lot of albumin (A3) whatever the eGFR, and with blood in the urine when the doctor suspects inflammation of the kidney filters. The international KDIGO guideline adds that a sustained fall in eGFR of more than 20 per cent should be looked into.
Stage 3 means eGFR is between 30 and 59, which is moderately reduced kidney function. Many people in stage 3 have no symptoms and live as before, and some stay stable for many years with good treatment.
Stage 3a (eGFR 45 to 59) and 3b (eGFR 30 to 44) are separated because the risk rises noticeably in 3b. In stage 3 most people are followed by their GP (fastlege) with blood and urine tests, blood pressure checks and often kidney protecting medicines. Some eventually get high potassium or phosphate and need dietary advice tailored to their blood tests. See Food with kidney failure.
Stage 2 (eGFR 60 to 89) is only chronic kidney disease if there are also signs of damage, most often albumin in the urine. Without such signs, an eGFR in this range is common, especially in older people. How the tests are taken is explained in How to detect kidney disease.
In stage 4 (eGFR 15 to 29) kidney function is severely reduced, and many people get symptoms such as tiredness, poor appetite, nausea, itching, restless legs and difficulty sleeping. Anaemia and disturbances in potassium, phosphate and acid in the blood become more common and are treated with medicines and diet.
In stage 4 your GP should contact a kidney specialist or consider doing so, and many people are then followed by a kidney specialist. This is also when the conversation starts about what will happen if the kidneys fail: dialysis, transplant or treatment without dialysis. Feel free to bring a family member to these conversations, see Supporting someone with kidney disease. Read more about the signs in Symptoms of kidney failure.
Stage 5 means kidney failure: eGFR is below 15, and the kidneys can no longer keep the blood clean on their own. When the symptoms can no longer be kept in check with medicines, dialysis or a new kidney is needed. For some, especially the oldest and frailest, treatment without dialysis can be the best choice.
The choice is made together with your kidney specialist and depends on age, health and what you want yourself. Read more in Dialysis, Kidney transplant and End-stage kidney failure, which covers treatment without dialysis and the last phase.
There is no single figure. Many people in stage 3 never need dialysis, and the risk depends mostly on how much albumin leaks and how fast eGFR falls. Your doctor can calculate your own risk of kidney failure over the next two and five years with a calculation called the KFRE (Kidney Failure Risk Equation).
In stages 4 and 5 the outlook also depends on age, the heart and which treatment you receive. Figures and explanations are in Kidney failure and life expectancy.
Kidney tissue that has been lost does not come back, but eGFR varies from test to test. Dehydration, acute illness and some medicines, such as anti-inflammatory painkillers, can give a temporarily lower value that improves again. That is why the tests are repeated before the stage is set.
When you start certain kidney protecting medicines, eGFR can fall a little in the first weeks. This is expected and is a sign that the pressure in the kidney filters is going down. Albumin in the urine can often be reduced with treatment, and then you move down an A category. The aim of treatment is for eGFR to fall as slowly as possible. Read about painkillers and the kidneys.
In the Nyrami app you enter your stage, eGFR and albumin, and get your values explained in words. You can see how they change over time, and the food scanner assesses potassium, phosphorus, sodium and protein in what you buy. The app is free for iPhone and Android.
Turns the advice into something you can use in the shop and the kitchen: scan food and see potassium, phosphorus and salt assessed for you, and follow your numbers over time. Free on iPhone and Android.
Most kidney disease is not inherited, but caused by high blood pressure and diabetes, which often run in families. Some kidney diseases are passed on directly, especially polycystic kidney disease and Alport syndrome. If a close relative has kidney disease, you should have your blood pressure, blood and urine checked.
Acute kidney injury often gets completely or almost completely better. Chronic kidney disease (CKD) usually does not go away, but its progress can often be slowed so much that many people never need dialysis. How long people live depends mostly on stage, albumin in the urine, age and the heart. With dialysis or a new kidney, life can still be good.
Chronic kidney disease (CKD) means the kidneys have been damaged or have worked less well than normal for at least three months. Around ten per cent of adults have it, most of them mildly and without noticing anything. The disease does not go away, but treatment can slow it down, often for many years.
