Chronic kidney disease (CKD) is a long-term condition in which the kidneys have abnormalities in their structure or function that persist for more than three months. Because the kidneys filter waste and extra fluid from the blood, ongoing kidney damage can gradually affect many parts of the body.

One of the challenges of chronic kidney disease is that it often develops without noticeable symptoms, particularly in its early stages. Blood and urine tests are therefore important for detecting CKD and monitoring kidney function. The two key markers commonly used are estimated glomerular filtration rate (eGFR) and urine albumin.

The most common CKD causes in adults are diabetes and high blood pressure. Other causes include certain kidney diseases, autoimmune conditions, infections, kidney stones with complications, inherited disorders, and some medicines or substances that can damage the kidneys.

Understanding CKD symptoms, causes, stages, and testing can help people recognize why routine kidney monitoring is important—especially when they have risk factors for kidney disease.

What Is Chronic Kidney Disease?

The kidneys perform several important functions. They filter the blood, remove waste and excess fluid, help regulate electrolytes and blood pressure, and contribute to other processes that keep the body functioning properly.

When kidney structure or function remains abnormal for more than three months, it may meet the definition of chronic kidney disease. CKD can range from mild kidney abnormalities to severe loss of kidney function.

CKD does not progress at the same rate in everyone. Some people remain stable for years, while others experience a gradual decline in kidney function. Not everyone with CKD develops kidney failure.

What Are the Symptoms of Chronic Kidney Disease?

Early CKD symptoms can be difficult to recognize because many people have few or no symptoms.

In fact, testing may be the only way to identify early kidney disease. As kidney function becomes more impaired, symptoms can become more noticeable.

Possible symptoms of more advanced CKD include:

• Swelling in the ankles, feet, legs, hands, or face
• Fatigue or low energy
• Changes in how often a person urinates
• Foamy urine
• Loss of appetite
• Nausea or vomiting
• Difficulty concentrating
• Sleep problems
• Muscle cramps
• Itchy or dry skin
• Unintentional weight loss
• Shortness of breath
• Chest discomfort

These symptoms are not specific to CKD and can occur with other medical conditions. Having one or more of them does not automatically mean a person has kidney disease.

Anyone concerned about symptoms or kidney health should discuss them with a qualified healthcare professional rather than attempting to diagnose CKD based on symptoms alone.

What Causes Chronic Kidney Disease?

There are many possible CKD causes, but two are particularly important in adults: diabetes and high blood pressure.

Diabetes

Diabetes can damage the small blood vessels and filtering structures in the kidneys when elevated blood glucose affects the kidneys over time.

Kidney disease caused by diabetes is known as diabetic kidney disease. Diabetes is one of the major reasons people develop CKD, making regular kidney monitoring important for people living with diabetes.

High Blood Pressure

High blood pressure can damage blood vessels and the kidney’s filtering system. Kidney damage can also contribute to further increases in blood pressure, creating a cycle that can worsen kidney health.

Other Causes

Other possible causes include:

• Glomerular diseases affecting the kidney’s filtering structures
• Polycystic kidney disease
• Autoimmune conditions such as lupus
• Certain infections
• Kidney stones with complications
• Previous acute kidney injury
• Some medicines or substances that can be toxic to the kidneys
• Heart or liver conditions affecting kidney function
• Genetic or inherited kidney disorders
• Certain cancers or related conditions
• Severe obesity
• Sickle cell disease
• Problems affecting the kidney’s blood supply

Identifying the underlying cause is important because CKD management can depend on what caused the kidney damage.

Who Is at Higher Risk for CKD?

Certain health conditions and family factors increase the likelihood of developing chronic kidney disease.

Risk factors include:

• Diabetes
• High blood pressure
• Cardiovascular disease
• Family history of kidney failure
• Previous kidney problems
• Certain inherited conditions

NIDDK recommends that people with important risk factors discuss kidney testing with a healthcare professional.

Routine testing can be particularly important because CKD may remain silent until kidney function has declined substantially.

How Is Chronic Kidney Disease Diagnosed?

Doctors use blood and urine tests to evaluate kidney health.

eGFR Blood Test

The estimated glomerular filtration rate (eGFR) estimates how well the kidneys filter blood.

It is calculated using information from blood tests, particularly serum creatinine, along with an estimating equation.

A persistently reduced eGFR can be evidence of CKD. However, a single abnormal result does not necessarily establish chronic kidney disease because kidney function can change temporarily for several reasons. CKD is generally identified when abnormalities persist for more than three months.

Urine Albumin Test

A urine test can measure albumin, a protein that normally remains in the bloodstream.

When kidney filters are damaged, albumin can leak into the urine. A commonly used test is the urine albumin-to-creatinine ratio (UACR). A UACR above 30 mg/g can indicate increased albumin in the urine and may be a marker of kidney disease.

Doctors may repeat abnormal results to determine whether the finding is persistent.

Other Tests

Depending on the suspected cause and the person’s health history, healthcare professionals may also use:

• Blood pressure measurements
• Blood tests for electrolytes and other substances
• Urinalysis
• Kidney imaging
• Additional blood or urine tests
• Tests directed at specific kidney diseases

The exact evaluation depends on the clinical situation.

Understanding Kidney Disease Stages

CKD is commonly classified using GFR categories from G1 through G5. Albuminuria is also categorized because kidney disease risk depends on more than eGFR alone.

KDIGO classifies CKD according to Cause, GFR category, and Albuminuria category, often abbreviated as CGA.

CKD Stage and eGFR

GFR Category	eGFR Range (mL/min/1.73 m²)	General Description
G1	≥90	Normal or high
G2	60–89	Mildly decreased
G3a	45–59	Mildly to moderately decreased
G3b	30–44	Moderately to severely decreased
G4	15–29	Severely decreased
G5	<15	Kidney failure

These categories describe kidney function and should not be interpreted in isolation. For example, an eGFR of 60 or higher does not by itself rule out CKD if other evidence of kidney damage is present. Conversely, an isolated eGFR result should not automatically be interpreted as chronic kidney disease without considering persistence and the broader clinical picture.

Albuminuria Categories

Albuminuria is also divided into categories:

Category	UACR	Description
A1	<30 mg/g	Normal to mildly increased
A2	30–300 mg/g	Moderately increased
A3	>300 mg/g	Severely increased

Higher levels of albumin in the urine can indicate greater kidney damage and are associated with increased risk of kidney disease progression.

This is why two people with the same eGFR may not have the same overall risk profile.

What Happens as CKD Progresses?

CKD can become more serious as kidney function declines, but progression varies considerably between individuals.

Factors associated with greater risk of progression include:

• Increasing albuminuria
• Declining eGFR
• Diabetes
• High blood pressure
• Other underlying kidney diseases

Healthcare professionals monitor kidney function and urine albumin over time rather than relying on a single test result.

Stage 1 and Stage 2

At these stages, eGFR may be normal or only mildly reduced. Importantly, CKD at these levels generally requires another marker of kidney damage or structural abnormality to establish the diagnosis.

People may have no noticeable symptoms.

Stage 3

Stage 3 is divided into G3a and G3b.

Kidney function is moderately reduced, and some people may begin to develop complications. Healthcare professionals may monitor kidney function, blood pressure, urine albumin, and other health indicators more closely.

Stage 4

At stage 4, kidney function is severely reduced.

People may have more noticeable symptoms or complications, and healthcare professionals may begin discussing preparation for possible kidney replacement therapy when appropriate.

Stage 5

Stage 5 corresponds to kidney failure, with an eGFR below 15 mL/min/1.73 m².

At this stage, healthcare professionals evaluate the person’s overall condition and discuss appropriate treatment options. For some people with kidney failure, treatment may include dialysis or kidney transplantation.

What Complications Can CKD Cause?

As kidney function declines, CKD can affect systems throughout the body.

Possible complications include:

• High blood pressure
• Cardiovascular disease
• Anemia
• Mineral and bone disorders
• Electrolyte abnormalities
• Metabolic acidosis
• Nutritional problems
• Fluid buildup
• Increased risk of acute kidney injury

CKD is also associated with an increased risk of cardiovascular disease, including heart attack and stroke.

The presence and severity of complications vary from person to person.

Can Chronic Kidney Disease Be Prevented or Slowed?

Not every case of CKD can be prevented because some causes are inherited or related to conditions that cannot be completely avoided.

However, managing conditions that contribute to kidney damage can help protect kidney health. Healthcare professionals may recommend approaches based on the underlying cause and the person’s overall health.

Important areas may include:

• Managing blood pressure
• Managing blood glucose when diabetes is present
• Monitoring kidney function
• Monitoring urine albumin
• Following the treatment plan prescribed by a healthcare professional
• Reviewing medicines with a healthcare professional when appropriate
• Maintaining healthy lifestyle habits
• Avoiding tobacco
• Following dietary recommendations appropriate to the individual’s kidney function and medical conditions

There is no single diet or treatment plan that is appropriate for everyone with CKD. Dietary and medication decisions should be individualized with a qualified healthcare professional.

NIDDK emphasizes that identifying CKD early and managing it appropriately may help protect kidney function and reduce the risk of complications.

When Should You Talk to a Healthcare Professional?

Because early CKD often causes no symptoms, people with risk factors should discuss appropriate kidney testing with a healthcare professional.

You should also seek medical advice if you develop concerning symptoms such as persistent swelling, significant changes in urination, unexplained fatigue, persistent nausea, shortness of breath, or other symptoms that may indicate a serious health problem.

People with known CKD should follow their healthcare team’s recommendations for monitoring kidney function and managing complications.

Urgent medical attention may be appropriate for severe shortness of breath, chest pain, confusion, severe weakness, or other potentially serious symptoms.

Frequently Asked Questions About Chronic Kidney Disease

1. What is chronic kidney disease?

Chronic kidney disease is a long-term abnormality of kidney structure or function that persists for more than three months and has implications for health. It can range from mild kidney abnormalities to kidney failure.

2. What are the early symptoms of CKD?

Many people have no symptoms during the early stages. Blood and urine testing may detect kidney disease before noticeable symptoms develop.

3. What are the most common causes of CKD?

Diabetes and high blood pressure are the leading causes of CKD in adults. Other causes include kidney diseases, autoimmune conditions, infections, inherited disorders, certain medicines, and complications from kidney stones.

4. What are the stages of chronic kidney disease?

CKD is classified into G1 through G5 based on eGFR, with G1 representing normal or high GFR and G5 representing kidney failure. Albuminuria categories are also used to provide a more complete assessment of CKD.

5. Can CKD be detected with a blood test?

A blood test can estimate kidney function using eGFR. A urine test for albumin provides additional information about kidney damage. Both are important parts of CKD evaluation.

6. Does everyone with CKD develop kidney failure?

No. CKD progresses differently from person to person, and some people never develop kidney failure. Risk depends on factors such as kidney function, albuminuria, underlying cause, and other health conditions.

7. Can chronic kidney disease be treated?

CKD can often be managed even though advanced chronic kidney damage generally cannot simply be reversed. Treatment focuses on the underlying cause, protecting remaining kidney function, managing complications, and reducing health risks. The appropriate approach depends on the individual and should be determined with a healthcare professional.

Conclusion

Chronic kidney disease can develop gradually and may remain unnoticed for years, which makes appropriate testing especially important for people at increased risk. Diabetes and high blood pressure are major CKD causes, while declining eGFR and increased urine albumin are important markers used to evaluate kidney health.

Understanding CKD symptoms, testing, and kidney disease stages can help people recognize the importance of regular medical care. CKD does not progress to kidney failure in everyone, and early identification and appropriate management may help protect kidney function and reduce complications.

If you are concerned about kidney disease, have diabetes or high blood pressure, or have a family history of kidney failure, discuss appropriate kidney testing and follow-up with a qualified healthcare professional.