Chronic Kidney Disease
Also known as: CKD, chronic renal failure, kidney disease
Medically reviewed by Nano Health Insights Editorial Team · Last reviewed 2026-06-23
Chronic kidney disease is kidney damage or an eGFR below 60 mL/min/1.73 m² for at least 3 months.
What it is
Chronic kidney disease is kidney damage or an estimated glomerular filtration rate (eGFR) below 60 mL/min/1.73 m² for at least 3 months. The key number is 3 months: CKD is defined by abnormalities that persist, not by a single abnormal blood test. CKD is a long-term condition in which the kidneys gradually lose their ability to filter waste, balance fluids and minerals, help control blood pressure, activate vitamin D, and support red blood cell production.
CKD is not one disease but a syndrome with many causes. Common causes include diabetes, high blood pressure, glomerular diseases, inherited disorders such as polycystic kidney disease, urinary tract obstruction, and repeated kidney injury. Early CKD often causes no symptoms, which is why it is frequently found on routine blood and urine testing rather than by how a person feels.
The older term "chronic renal failure" is less precise and is used less often now. Many people with CKD do not have kidney failure. Kidney failure usually refers to very advanced loss of function, often when dialysis or kidney transplantation may be needed.
A practical way to classify CKD is by GFR stage and albuminuria stage:
| Measure | Categories | What it means |
|---|---|---|
| eGFR | G1 to G5 | Lower eGFR generally means worse kidney function |
| Urine albumin | A1 to A3 | Higher albumin in urine generally means more kidney damage and higher risk |
This combined staging helps estimate the risk of progression, cardiovascular disease, and complications.
How it works
Healthy kidneys filter blood through millions of nephrons. They remove metabolic waste, regulate sodium, potassium, and acid-base balance, and adjust body water. They also produce hormones involved in blood pressure control and red blood cell production.
In CKD, ongoing injury damages nephrons. The remaining nephrons initially compensate by filtering more, but over time this adaptation can contribute to further scarring. Depending on the cause, damage may affect the glomeruli, tubules, interstitium, blood vessels, or urinary outflow tract.
As kidney function declines, several problems can develop:
- Waste retention: urea and other toxins build up.
- Fluid imbalance: swelling, high blood pressure, or shortness of breath can occur.
- Electrolyte problems: potassium may rise; acid can accumulate.
- Hormonal effects: reduced erythropoietin can cause anemia.
- Bone and mineral disorders: altered vitamin D, calcium, and phosphate balance can weaken bone and affect blood vessels.
CKD also raises the risk of cardiovascular disease. In many patients, the risk of heart attack, stroke, or heart failure is as important as the risk of eventually needing dialysis.
Evidence and uses
The main goals of CKD care are to identify the cause, slow progression, reduce cardiovascular risk, and treat complications. Strong evidence supports several approaches, especially when tailored to the cause and stage.
Common evidence-based management steps include:
| Approach | Why it matters |
|---|---|
| Blood pressure control | Slows kidney damage and lowers cardiovascular risk |
| Diabetes management | Reduces progression in diabetic kidney disease |
| ACE inhibitors or ARBs in appropriate patients | Lower albuminuria and help protect kidney function |
| SGLT2 inhibitors in selected patients | Reduce CKD progression and cardiovascular events in many patients |
| Avoiding nephrotoxins | Helps prevent additional kidney injury |
| Diet and lifestyle measures | Support blood pressure, diabetes, and fluid balance |
Treatment is not the same for everyone. Some people mainly need risk-factor control and monitoring. Others need treatment for anemia, metabolic acidosis, mineral and bone disorder, or preparation for kidney replacement therapy.
Symptoms, when they occur, may include fatigue, poor appetite, nausea, itching, ankle swelling, muscle cramps, sleep problems, and changes in urination. These symptoms are not specific to CKD and usually become more noticeable in later stages.
In India, CKD is an important public health issue because diabetes and hypertension are common. India-relevant care often includes attention to salt intake, over-the-counter painkiller use, dehydration risk, and access to regular creatinine and urine albumin testing. Nutritional advice should be individualized, especially in people who follow vegetarian diets or have limited food access.
Diagnosis / how it's measured
CKD is diagnosed using a combination of history, examination, blood tests, urine tests, and sometimes imaging or kidney biopsy.
The core tests are:
- Serum creatinine with eGFR calculation: estimates filtering capacity.
- Urine albumin-to-creatinine ratio (uACR): detects albumin leakage, an early sign of kidney damage.
- Persistence over time: abnormalities must be present for at least 3 months.
Other tests may include electrolytes, bicarbonate, hemoglobin, calcium, phosphate, parathyroid hormone, ultrasound, and tests for autoimmune or inherited causes when indicated.
A single abnormal creatinine does not always mean CKD. Acute kidney injury, dehydration, infection, some medicines, and lab variation can temporarily change kidney function. That is why repeat testing matters.
Typical CKD staging by eGFR is:
| Stage | eGFR (mL/min/1.73 m²) |
|---|---|
| G1 | 90 or higher, with other evidence of kidney damage |
| G2 | 60-89, with other evidence of kidney damage |
| G3a | 45-59 |
| G3b | 30-44 |
| G4 | 15-29 |
| G5 | Below 15 |
Albuminuria is commonly grouped as A1, A2, and A3, with higher categories indicating greater risk.
When to see a clinician
See a clinician if you have diabetes, high blood pressure, cardiovascular disease, a family history of kidney disease, recurrent kidney stones, or long-term use of medicines that can affect the kidneys, such as NSAID pain relievers. Screening is especially important because early CKD may have no symptoms.
Seek prompt medical care if you have swelling, reduced urine output, blood in the urine, persistent vomiting, severe fatigue, shortness of breath, confusion, or very high blood pressure. People with known CKD should ask before starting new medicines, supplements, or herbal products because some can worsen kidney function or require dose adjustment.
Referral to a nephrologist is often appropriate for advanced CKD, rapidly falling eGFR, significant albuminuria, resistant hypertension, unclear cause, or difficult complications such as anemia, high potassium, or bone-mineral problems.
Limitations and open questions
CKD is common, but it is not always straightforward to diagnose or predict. eGFR is an estimate, not a direct measurement, and can be affected by age, muscle mass, diet, and laboratory methods. Albuminuria can vary from day to day, so repeat testing is often needed.
Another limitation is that CKD progression is highly variable. Some people remain stable for years, while others decline faster despite treatment. Risk prediction improves when eGFR and albuminuria are considered together, but uncertainty remains at the individual level.
Research continues on earlier detection, better risk models, and treatments for non-diabetic CKD and inflammatory kidney diseases. There is also ongoing work on how best to adapt CKD screening and long-term care in lower-resource settings, including parts of India, where late diagnosis and limited access to nephrology care remain important barriers.
FAQs
What is the difference between chronic kidney disease and kidney failure?
Chronic kidney disease is a broad term for long-term kidney damage or reduced kidney function lasting at least 3 months. Kidney failure usually refers to very advanced CKD, often stage G5, when eGFR is below 15 mL/min/1.73 m² and dialysis or transplant may be considered. Not everyone with CKD progresses to kidney failure.
Can chronic kidney disease be reversed?
CKD is usually not fully reversible because it often involves permanent scarring or loss of functioning nephrons. However, treatment can slow progression, reduce albuminuria, and manage complications. In some cases, a temporary decline in kidney function is due to dehydration or medication effects rather than true CKD, which is why repeat testing over 3 months matters.
What are the early symptoms of CKD?
Early CKD often causes no symptoms at all. When symptoms appear, they may include fatigue, ankle swelling, poor appetite, nausea, itching, or changes in urination, but these are not specific to kidney disease. Blood tests for creatinine and urine tests for albumin are often the first clues.
What tests are used to diagnose chronic kidney disease?
The main tests are serum creatinine with eGFR and a urine albumin-to-creatinine ratio. To diagnose CKD, the abnormality must persist for at least 3 months. Doctors may also order kidney ultrasound, electrolyte tests, hemoglobin, and sometimes autoimmune or genetic testing depending on the suspected cause.
What should people with CKD avoid?
Many people with CKD are advised to avoid dehydration, smoking, and unnecessary use of NSAID pain medicines such as ibuprofen or diclofenac because these can worsen kidney function. Some medicines, supplements, and herbal products may need dose adjustment or should be avoided entirely in reduced eGFR. A clinician or pharmacist should review all prescription, over-the-counter, and traditional products, especially before starting something new.