5 stages of chronic kidney disease: How kidney function declines

• Chronic kidney disease has five stages, ranging from early kidney damage to kidney failure.

• The stages are assessed mainly through eGFR blood tests and urine tests for albumin; early CKD may have no symptoms.

• Early diagnosis, regular monitoring and treatment of conditions such as diabetes and high blood pressure can help slow disease progression.

Chronic kidney disease (CKD) is a condition in which the kidneys become damaged and gradually lose their ability to filter waste and excess fluid from the blood effectively.

The kidneys also help regulate blood pressure, balance minerals in the body and support red blood cell production. When they are damaged, these functions can become affected over time.

Chronic kidney disease is classified into five stages, ranging from early kidney damage to kidney failure. The stage helps healthcare professionals understand how well the kidneys are working, assess the risk of complications and determine appropriate treatment.

However, kidney disease does not progress at the same rate in everyone. Some people remain stable for years, while others experience a faster decline in kidney function.

According to the National Kidney Foundation, doctors assess kidney function using a blood test that estimates the glomerular filtration rate (eGFR), alongside urine tests that check for albumin, a protein that can leak into the urine when the kidneys are damaged.

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Here are the five stages of chronic kidney disease and what they mean.

At stage 1, the kidneys generally filter blood well, with an eGFR of 90 or higher. However, there must also be evidence of kidney damage, such as persistent albumin in the urine or an abnormality detected through imaging.

An eGFR of 90 or higher alone does not mean a person has chronic kidney disease.

Many people at this stage have no obvious symptoms and may discover the condition during routine medical tests.

Early detection is important because managing the underlying cause, such as high blood pressure or diabetes, may help reduce the risk of further damage.

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Stage 2 CKD is characterised by an eGFR of 60 to 89, together with evidence of kidney damage that persists over time.

The kidneys may still perform many of their functions adequately, and most people at this stage do not experience noticeable symptoms.

A doctor may recommend regular monitoring, blood pressure control, appropriate treatment and lifestyle changes based on the cause of the damage and the person's overall health.

An eGFR between 60 and 89 does not automatically mean someone has CKD. Other evidence of kidney damage is needed to establish the diagnosis.

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Stage 3 is divided into two categories: stage 3a and stage 3b.

Stage 3a: The eGFR is between 45 and 59, indicating a mild to moderate reduction in kidney function.

Stage 3b: The eGFR is between 30 and 44, indicating a moderate to severe reduction in kidney function.

At this stage, the kidneys may struggle more to remove waste and maintain the body's balance of fluids and minerals. Some people may begin experiencing symptoms such as tiredness, swelling or changes in urination, although symptoms vary and may be absent.

The risk of complications, including anaemia, bone and mineral problems, and cardiovascular disease, can also increase as kidney function declines.

Treatment focuses on managing the cause of kidney disease, monitoring kidney function, addressing complications and reducing the risk of further deterioration.

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At stage 4, the eGFR falls to between 15 and 29, indicating a severe loss of kidney function.

Waste products and excess fluid may build up in the body, and complications become more likely.

Possible symptoms include swelling in the legs or feet, persistent tiredness, nausea, reduced appetite, itching and difficulty concentrating. However, these symptoms are not exclusive to kidney disease and require medical assessment.

People at this stage generally need close medical monitoring and a treatment plan designed to slow further damage and manage complications.

Healthcare professionals may also begin discussing future treatment options, including dialysis or kidney transplantation, if kidney failure develops.

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Stage 5 CKD, also known as kidney failure, occurs when the eGFR falls below 15 and the reduction is persistent, or when a person is receiving dialysis for kidney failure.

At this stage, the kidneys have lost much of their ability to remove waste and excess fluid and maintain the body's chemical balance.

Symptoms may include severe fatigue, nausea, loss of appetite, swelling, itching, shortness of breath and changes in urination. The symptoms and their severity differ from person to person.

Treatment may involve dialysis, a kidney transplant or other forms of supportive care, depending on the person's medical condition and circumstances. Not everyone with stage 5 CKD begins dialysis immediately; treatment decisions depend on symptoms, complications and clinical assessment.

Kidney failure is serious, but appropriate treatment can help people manage the condition.

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Although existing kidney damage may not always be reversible, treatment and monitoring can help slow the progression of CKD in many people.

Steps that may help include:

• Keeping blood pressure within the target range recommended by a healthcare professional.

• Managing diabetes and other conditions that can damage the kidneys.

• Taking prescribed medicines as directed and avoiding self-medication, particularly with medicines that may harm the kidneys.

• Following an appropriate eating plan and limiting salt when advised.

• Attending follow-up appointments and completing recommended blood and urine tests.

People at increased risk, including those with diabetes, high blood pressure or a family history of kidney failure, should discuss appropriate kidney screening with a healthcare professional.

The key point: Chronic kidney disease can develop without obvious symptoms, particularly in its early stages. Regular testing for people at risk can help identify kidney problems before they become more advanced.