Chronic Kidney Disease (CKD): Stages, Symptoms and Treatment

What chronic kidney disease is

Your kidneys filter about 50 gallons (190 liters) of blood a day. They remove waste and excess fluid, balance salts and acid, help control blood pressure, keep bones healthy and make erythropoietin, the hormone that tells the bone marrow to make red blood cells.

In chronic kidney disease, the tiny filtering units (nephrons) are gradually lost. The remaining nephrons work harder to compensate, which keeps blood tests near normal for a long time but strains them further. That is why CKD is often called a silent disease: people can lose more than half their kidney function before they feel anything.

CKD is defined as either of these for more than 3 months:

• an eGFR (estimated glomerular filtration rate) below 60 mL/min/1.73 m², or
• signs of kidney damage, most often albumin (protein) in the urine, blood in the urine or abnormal kidney structure on a scan.

The 3-month rule separates CKD from acute kidney injury, a sudden drop in function that often recovers. For a broader overview of kidney disorders, see kidney disease.

CKD stages by eGFR

Doctors stage CKD using two numbers: the eGFR ("G" stage) and the urine albumin-to-creatinine ratio ("A" stage). Both predict how fast the disease will progress and the risk of heart disease.

A person with "G3a A2" CKD has an eGFR of 45 to 59 and moderate protein leak. Many people stay in stage 3 for life and never need dialysis, especially with good treatment.

Chronic kidney disease symptoms

Stages 1 to 3 usually cause no symptoms. When symptoms appear, typically at stage 4 or 5, they come from waste, fluid and hormone imbalances:

• tiredness, weakness and trouble concentrating
• swelling of the ankles, feet or around the eyes (peripheral edema)
• shortness of breath from fluid in the lungs or anemia
• persistent itching, often worse at night
• poor appetite, nausea, a metallic taste and weight loss
• muscle cramps and restless legs
• needing to urinate at night, foamy urine, or passing less urine
• feeling cold, pale skin and difficulty sleeping

Anemia in chronic kidney disease

Damaged kidneys make less erythropoietin, so many people with stage 3b to 5 CKD develop anemia. Symptomatic anemia causes fatigue, breathlessness on exertion, a fast heartbeat, dizziness and feeling cold. Iron deficiency often adds to it. Treatment is iron (tablets or IV) first, then erythropoiesis-stimulating agent (ESA) injections if hemoglobin stays low. Read more in anemia due to chronic kidney disease.

Causes and risk factors

• Diabetes: the leading cause. High glucose damages the glomeruli (diabetic kidney disease).
• High blood pressure: both a cause and a consequence of CKD. See high blood pressure.
• Glomerular diseases: IgA nephropathy, lupus nephritis and other forms of glomerulonephritis.
• Inherited conditions: polycystic kidney disease, Alport syndrome.
• Blockage or reflux: enlarged prostate, repeated kidney stones, childhood vesicoureteral reflux.
• Medicines and toxins: long-term NSAID use, lithium, some chemotherapy drugs.
• Repeated acute kidney injury.

Higher risk also comes with age over 60, heart disease, obesity, smoking, a family history of kidney failure, and Black, Hispanic, Native American and South Asian ancestry, mostly because diabetes and high blood pressure are more common in these groups.

How CKD is diagnosed

Screening is simple and is recommended at least yearly for people with diabetes or high blood pressure.

1. eGFR blood test: calculated from creatinine (and sometimes cystatin C), age and sex. Current US equations no longer use race.
2. Urine ACR: a spot urine sample measures albumin. A raised result is confirmed on repeat testing.
3. Urinalysis: checks for blood, protein and infection.
4. Kidney ultrasound: looks at size, cysts, scarring and blockage.
5. Further blood tests: potassium, bicarbonate, calcium, phosphate, parathyroid hormone, hemoglobin and lipids.
6. Kidney biopsy: only when the cause is unclear and the result would change treatment.

A nephrologist (kidney specialist) is usually involved when eGFR falls below 30, ACR is above 300 mg/g, eGFR drops quickly, or the cause is uncertain.

CKD treatment: how to slow it down

Medicines that protect the kidneys

• ACE inhibitors or ARBs: lower blood pressure and reduce protein leak. Blood tests check potassium and creatinine after starting.
• SGLT2 inhibitors (such as dapagliflozin or empagliflozin): slow CKD progression and cut heart failure risk, with or without diabetes.
• Finerenone: for people with type 2 diabetes and albuminuria, added to the above.
• Statins: lower the high heart attack and stroke risk that comes with CKD.

Blood pressure, blood sugar and lifestyle

• Blood pressure targets are usually below 130/80 mmHg, set individually.
• Good diabetes control, avoiding low blood sugar.
• Stop smoking, stay active and aim for a healthy weight.
• Lower salt intake. A renal dietitian can advise on protein, potassium and phosphorus, which matter more in later stages.

Medicine safety

• Avoid regular NSAIDs (ibuprofen, naproxen). Acetaminophen (paracetamol) at the label dose is usually the safer pain reliever.
• Ask a pharmacist before taking supplements, herbal products or laxatives and enemas containing phosphate or magnesium.
• Many drug doses need adjusting to your eGFR.
• "Sick day rules": if you are vomiting or have diarrhea, your doctor may tell you to pause certain medicines until you can eat and drink again.

Treating complications

Anemia, bone and mineral disorders (phosphate binders, vitamin D), acidosis (sodium bicarbonate), high potassium and fluid overload (diuretics) are managed as they arise.

Stage 5: dialysis, transplant or conservative care

When eGFR nears 15 or symptoms build, options are hemodialysis, peritoneal dialysis at home, a kidney transplant (ideally before dialysis starts, from a living donor), or conservative care focused on comfort for people who choose not to have dialysis. See kidney failure for details.

Complications

• Heart disease: people with CKD are more likely to die of heart disease than to reach kidney failure.
• High potassium, which can cause dangerous heart rhythms.
• Fluid overload and swelling.
• Bone disease from calcium, phosphate and parathyroid hormone imbalance.
• Anemia.
• Metabolic acidosis, gout and nerve damage.
• Higher risk from infections and from medicines that build up.

Outlook

Most people with CKD, especially stages 1 to 3, never need dialysis. Progression varies widely: some lose 1 mL/min per year, similar to normal aging, and others lose much more. Low protein in the urine, controlled blood pressure and modern kidney-protecting drugs all improve the outlook. Regular eGFR and ACR checks show whether treatment is working.

Frequently asked questions

What are the 5 stages of chronic kidney disease?

Stage 1 is an eGFR of 90 or more with signs of damage, stage 2 is 60 to 89, stage 3a is 45 to 59, stage 3b is 30 to 44, stage 4 is 15 to 29 and stage 5 is below 15, which is kidney failure. Doctors also grade urine protein from A1 to A3.

What are the first signs of chronic kidney disease?

Usually there are none. Early CKD is found by an eGFR blood test or protein in a urine test. When symptoms do appear, the first ones are often tiredness, ankle swelling, foamy urine, needing to urinate at night and itching. That is why people with diabetes or high blood pressure need yearly testing.

Can chronic kidney disease be reversed?

Scarred kidney tissue does not heal, so most CKD cannot be reversed. However, eGFR can improve slightly when blood pressure, blood sugar or a blockage is treated, and progression can be slowed dramatically with ACE inhibitors or ARBs, SGLT2 inhibitors and good risk-factor control.

Why does chronic kidney disease cause anemia?

Healthy kidneys make erythropoietin, which signals the bone marrow to produce red blood cells. Damaged kidneys make less of it, and iron deficiency and blood loss add to the problem. Symptomatic anemia causes fatigue and breathlessness and is treated with iron and, if needed, ESA injections.

Is chronic renal failure the same as CKD?

"Chronic renal failure" is an older term. Today doctors say chronic kidney disease for all stages and reserve "kidney failure" for stage 5, when eGFR is below 15 or dialysis or a transplant is needed.

How long can you live with stage 3 CKD?

Many people live a normal lifespan with stage 3 CKD, and most never reach kidney failure. The biggest risk at this stage is heart disease, so controlling blood pressure, cholesterol, blood sugar and smoking matters as much as protecting the kidneys.