Medically reviewed by Kashif J. Piracha, MD
Chronic kidney disease (CKD) is divided into five stages, ranging from stage 1 to stage 5. Each stage is determined by a blood test known as the estimated glomerular filtration rate (eGFR), which establishes how well your kidneys filter waste and excess fluid from your blood.
With each stage of CKD, the function of your kidneys progressively worsens and requires different treatments to slow down kidney damage and to keep them working for as long as possible. Renal (kidney) failure occurs when the kidneys are no longer functioning, at which time dialysis or a kidney transplant is needed to keep you alive.
This article explains how chronic kidney disease is staged and what each stage means regarding treatment, complications, and the risk of renal failure.
Acute vs. Chronic Kidney Disease
Acute kidney disease, more commonly referred to as acute kidney injury (AKI), is the sudden, severe, and typically reversible loss of kidney function caused by things like severe dehydration, medication side effects, or urinary tract obstruction by a kidney stone.
How Is Chronic Kidney Disease Staged?
Chronic kidney disease is staged to categorize the severity of the loss of renal function and to direct the appropriate course of treatment.
The five stages are categorized based on the results of an eGFR blood test. The eGFR is a mathematical calculation used to determine how much blood is filtered clean through the filtering units of your kidneys, called glomeruli, every minute.
The calculation is based on a serum creatinine blood test, which measures the amount of a muscle breakdown product called creatinine in your blood. If your kidneys are not functioning as they should, creatinine will not be cleared from the body in urine and levels will start to increase.
Despite the usefulness of the test, creatinine levels alone cannot determine the stage of CKD as "normal" creatinine levels can vary based on your body size and other factors. Creatinine levels also naturally decline with age.
The eGFR test overcomes this by calculating the rate of filtration based on five key factors:
Your serum creatinine level
Your height and weight
Your race and/or ethnicity
The eGFR offers a standardized means of measuring kidney function across all body sizes, ages, sexes, and racial/ethnic groups.
In most adults, a normal eGFR is 90 or above. As kidney function starts to decline, the eGFR will also decrease. Based on these findings, CKD can be staged as follows:
90 or higher
Mild kidney damage
60 to 89
Mild kidney damage
45 to 59
Mild to moderate kidney damage
30 to 44
Moderate to severe kidney damage
15 to 29
Severe kidney damage
CKD Stages 1 Through 5 Based on eGFR
In the early stages of CKD (stages 1 to 3), your kidneys are still largely functional. In the later stages (stages 4 and 5), your kidneys have to work harder to filter blood and may stop working altogether.
The staging of CKD is important because it informs the treatment plan and directs which measures should be used based on the eGFR calculation and the rate by which the eGFR declines over time.
Stage 1 CKD
With stage 1 CKD, the damage to your kidneys is mild. Because of this, you may not have symptoms.
You will invariably have an increased amount of protein in your urine (proteinuria). This is because damaged glomeruli allow more protein to escape into your urine rather than being filtered and returned to the bloodstream.
Typically, there are no symptoms associated with stage 1 CKD. While certain changes may be seen on ultrasound or in urine tests, they may not cause observable symptoms. The one exception is foamy urine caused by excessive amounts of a protein called albumin in your urine.
Treatment at stage 1 is largely focused on managing the underlying cause of kidney damage to slow disease progression.
This may include:
Controlling your blood glucose (sugar) if you have diabetes
Stage 2 CKD
With stage 2 CKD, the damage to your kidneys is still mild, but the kidneys are starting to function at less than their optimal capacity. As symptoms generally do not start until stage 3, many people with stage 2 CKD may not know they have kidney disease.
If symptoms do occur, they may again involve foamy urine and/or an increased risk of urinary tract infections (UTIs), especially in females.
With stage 2 CKD, your healthcare provider may recommend certain lifestyle changes in addition to managing your blood pressure and diabetes.
These may include:
Losing weight with a healthy diet and routine exercise if you are overweight or have obesity
Quitting cigarettes, which can lower blood pressure and reduce stress on the kidneys
Getting plenty of sleep and managing stress, both of which also influence blood pressure
Starting diabetes or blood pressure medications such as angiotensin-converting enzyme (ACE) inhibitors, angiotensin II receptor blockers (ARBs), sodium-glucose co-transporter 2 (SGLT2) inhibitors, or Kerendia (finerenone) which can slow or stop CKD progression
Stage 3 CKD
Stage 3 CKD is when your kidneys sustain significant enough damage to start producing symptoms. There are two substages. Stage 3a is kidney function loss that's mild to moderate. Stage 3b is kidney function loss that's moderate to severe.
Increasing damage to the kidneys can cause the loss of important nutrients like calcium and vitamin D, affecting bone health. It can also cause a buildup of acid in your blood (metabolic acidosis) and a decrease in red blood cells (anemia).
Symptoms of stage 3a CKD may include:
Urinating more often or less often than usual
Fatigue and tiredness
Dry and/or itchy skin
Loss of appetite
Unintended weight loss
With stage 3b, a person may additionally experience:
Muscle aches or cramps
Shortness of breath
Peripheral neuropathy (numbness or prickly sensations in the hands or feet)
Peripheral edema (swelling in the arms, legs, hands, or feet)
With stage 3 CKD, additional interventions will likely be needed to control blood pressure and/or blood sugar while reducing the risk of disease complications.
These may include:
Taking a statin drug to reduce cholesterol
Taking a diuretic to promote urination, reduce blood pressure, and reduce peripheral edema
Taking calcium and vitamin D supplements to keep your bones strong
Taking iron supplements to help manage anemia
Stage 4 CKD
Stage 4 CKD means that your kidneys are moderately to severely damaged, increasing the likelihood of disease complications like anemia, high blood pressure, bone disease, and metabolic acidosis.
The damage can also cause the excessive buildup of potassium (hyperkalemia) and phosphorus (hyperphosphatemia) in your blood, both of which can contribute to heart rhythm disorders and an increased risk of heart disease or stroke.
In addition to an increased risk of the above-listed symptoms, stage 4 CKD can also cause:
Persistent lower back pain
Insomnia (trouble sleeping)
Breath that smells fishy or like ammonia or urine
Hematuria (blood in the urine)
Additional aggressive treatments will be started to preserve what kidney function you have.
Changing your diet to restrict how much protein, phosphorus, and potassium you consume
Taking erythropoiesis-stimulating agents (ESAs) to treat severe anemia
Treating stage 4 CKD can be challenging because many of the medications you take to manage high blood pressure and diabetes can suddenly place stress on the kidneys and promote kidney damage.
Stage 5 CKD
Stage 5 is the most advanced stage of CKD, in which you experience kidney failure. Also known as end-stage renal failure (ESRD), stage 5 CKD is when your kidneys are no longer functional enough to support your body's needs.
Stage 5 CKD is associated with uremia, a potentially dangerous condition in which waste products build up in your blood.
This can lead to potentially severe symptoms like:
Dyspnea (shortness of breath)
Pruritus (itchiness), often severe
Chest pain or pressure
Vomiting or diarrhea
Vomiting or diarrhea
At this stage of the disease, the only options for treatment are:
Kidney transplantation, either from a living donor or a recently deceased donor
In the absence of treatment, death will eventually occur, However, the time of progression to death is variable.
Related: Kidney Failure: What to Expect
CKD Stages Progression
Chronic kidney disease usually progresses slowly over the course of years. Even so, many people do not realize that they have the disease until it is advanced and symptoms are severe enough to seek treatment. Of the estimated 37 million adults living with CKD in the United States, 1 in 9 people are unaware that they have the disease.
Even so, the progression of CKD can be slowed or even stopped if the disease is diagnosed and treated early. With the appropriate treatment and healthy life changes, many people with stage 1, 2, or 3 CKD will never progress to stage 4 or 5.
This is evidenced by a 2021 study in the Clinical Kidney Journal. It showed that, of the 88,766 people with CKD and diabetes, only 5% to 8.4% showed any signs of progression over three years. The rapid progression of CKD—defined as a progression over two CKD stages within four years—is even less common, affecting only 2% of the study population.
Among the factors that can increase the risk of CKD progression are:
A sustained decline in eGFR
A decline in eGFR of 25% or greater from the baseline result
Having uncontrolled high blood pressure
Having chronic metabolic acidosis
Being a current smoker
Having a lower body mass index (BMI)
Being over 70 is also a factor, given that aging is associated with a natural decline in kidney function and the progression of chronic diseases like diabetes.
Effect of CKD on Life Expectancy
Chronic kidney disease is one of the leading causes of mortality (death) worldwide and one of the few noncommunicable diseases (those not passed to others through contact) in which annual deaths worldwide have increased over the past two decades.
In the United States, deaths from CKD are mainly due to heart disease,
CKD and heart disease often co-occur as they share many of the same risk factors, including high blood pressure, diabetes, and older age. Nearly one-third of the 1,938,505 deaths reported in people with CKD in the United States from 1999 to 2020 were due to heart disease.
Based on a 2023 review of studies involving 210,748 adults in the United States, CKD independently increases the risk of death from heart disease by more than threefold.
Other common causes of death in people with CKD include:
How Long Can I Live With ESRD?
The risk of death with stage 5 CKD is influenced by the treatment. According to a 2021 study in Seminars of Vascular Surgery, the five-year survival rate for people on hemodialysis is 41.4% (meaning that 41.4% will live for at least five years). By contrast, the five-year survival rate for those who undergo a kidney transplant is between 83.4% and 93.8%,
Follow-Up and Monitoring CKD Stages
If you are diagnosed with CKD, it is essential to monitor your eGFR and other kidney function tests regularly. Depending on your CKD stage, this may involve testing at least once annually. If and when CKD progresses, more frequent testing may be needed.
The testing should involve the following blood and urine tests:
Urine albumin-to-creatinine ratio (UACR)
Routine testing may be recommended every four to six months if albumin levels are high and/or you have stage 3 CKD or higher.
Some health experts recommend testing every two months for people with stage 4 CKD and every month for those with stage 5 CKD.
Is Chronic Kidney Disease Reversible?
Although CKD is irreversible, it is possible for your eGFR to improve. Studies suggest that up to 8% of cases categorized as stage 5 will regress to stage 4 within two years.
However, this is not because your kidney function has suddenly improved but more often because a factor involved in the eGFR calculation has changed. This might include a change in your body weight or the resolution of an acute kidney injury.
A regression in your eGFR won't necessarily alter the recommended treatments.
Chronic kidney disease has five stages. Stages 1 through 3 are often asymptomatic. Symptoms more often become apparent by stage 4. By stage 5, you are said to have end-stage renal disease (ESRD), in which you need either dialysis or a kidney transplant to survive.
The five stages of CKD are determined by the results of an EGFR test. The test estimates how much blood is filtered through your kidneys every minute.
Read the original article on Verywell Health.