Chronic Kidney Disease: Stages, Symptoms, Causes & Treatments

Let me start with a number that reframes everything: 37 million.

That’s roughly how many Americans have chronic kidney disease, about 1 in 7 adults. More than 90% of people with early-stage chronic kidney disease have no idea they have it. The kidneys don’t send pain signals the way the heart does during a heart attack. They compensate quietly for years as function declines, until the damage is large enough that symptoms become impossible to ignore.

By then the treatment options have narrowed. That’s why the story of CKD is mostly a story of detection: catching it at Stage 1 or 2, when eGFR is still above 60 and the full range of interventions is on the table, rather than finding it at Stage 4, when the conversation has already turned to dialysis planning.

This article walks through the five chronic kidney disease stages and their eGFR thresholds, the causes ranked by how common they are, the latest treatment advances (including the 2021 FDA approvals that changed the field), and what the CKD diet actually requires, which is more nuanced than most general-audience articles let on.

Chronic Kidney Disease Stages: eGFR Values and What They Mean

Quick Answer: chronic kidney disease is sorted into 5 stages based on eGFR (estimated glomerular filtration rate, measured in mL/min/1.73m²). Stage 1 (eGFR ≥90) is kidney damage with preserved function, Stage 3 is the most common diagnosed stage, and Stage 5 (eGFR <15) is kidney failure. eGFR is calculated from a serum creatinine blood test combined with age and sex. A separate measure, UACR (urine albumin-creatinine ratio), catches kidney damage even when eGFR is still normal.

CKD staging (KDIGO criteria):

Understanding eGFR in your labs: A standard blood chemistry panel includes serum creatinine, and your doctor or lab report may add an eGFR calculation. The normal range is usually above 60, but optimal is above 90. An eGFR between 60 and 89 only counts as CKD when it comes with kidney damage markers (protein in urine, blood in urine, or structural abnormalities on imaging). On its own, it may simply reflect normal aging.

UACR, the early warning test: The urine albumin-creatinine ratio (UACR) detects tiny amounts of albumin protein leaking from the kidney filters, the first sign of damage and often visible before eGFR drops. A UACR above 30 mg/g points to early kidney damage. Above 300 mg/g (macroalbuminuria) signals more significant damage and a higher risk of fast progression. The test costs under $20 and can flag chronic kidney disease years before eGFR declines, but it isn’t part of standard annual labs unless you specifically ask for it. Anyone with diabetes or hypertension should request it at every annual exam.

eGFR trajectory matters as much as the value: An eGFR of 45 that has held steady for 5 years carries a very different outlook than an eGFR of 45 that fell from 65 in 18 months. Rapid decline (more than 5 mL/min per year) is a clinical emergency that calls for immediate nephrology referral and more aggressive treatment.

Chronic Kidney Disease Causes, Ranked by Frequency

Quick Answer: Diabetes and high blood pressure together cause roughly 70% of all CKD in the United States. Glomerulonephritis and polycystic kidney disease account for most of the remaining genetic and immune-mediated cases. Modifiable risk factors, including NSAID overuse, obesity, and smoking, drive a meaningful but underappreciated share of the burden. Diabetic kidney disease is clinically distinct from other causes and now has the most FDA-approved nephroprotective therapies.

1. Diabetic kidney disease (DKD), about 44% of all new dialysis cases High blood glucose damages the glomerular basement membrane and causes hyperfiltration, where the kidneys work too hard early on, which paradoxically speeds up the damage and leads to progressive proteinuria. DKD is defined by the combination of diabetes, albuminuria, and declining eGFR with no other explanation. The UACR test is the primary screening tool, and the American Diabetes Association recommends annual UACR testing in all diabetic patients.

The good news is that DKD now has the most treatment options of any CKD cause, including SGLT2 inhibitors and GLP-1 receptor agonists (semaglutide, in Ozempic and Wegovy, showed kidney-protective effects in the FLOW trial). More on these in the treatment section.

2. Hypertensive nephrosclerosis, about 29% of chronic kidney disease Uncontrolled high blood pressure damages the small arteries supplying the kidneys, which reduces perfusion and gradually scars kidney tissue. The blood pressure target in CKD is below 130/80 mmHg under current KDIGO guidance, stricter than general hypertension targets. ACE inhibitors and ARBs are the preferred antihypertensive class for CKD because they lower intraglomerular pressure, the mechanical strain on the kidney filters, on top of their blood-pressure-lowering effect.

3. Glomerulonephritis, the leading cause in young adults Inflammation of the glomeruli (the tiny filtering units) can be triggered by infections (post-streptococcal), autoimmune disease (lupus nephritis, IgA nephropathy), or have no identifiable cause. IgA nephropathy is the most common form globally. New targeted therapies for it (sparsentan, iptacopan) received FDA approval in 2023 and 2024, relevant for the subset of chronic kidney disease driven by this mechanism.

4. Polycystic kidney disease (PKD) The most common genetic cause of CKD. Autosomal dominant PKD (ADPKD) produces bilateral fluid-filled cysts that gradually replace kidney tissue. Tolvaptan (Jynarque) is the only FDA-approved drug that slows cyst growth in ADPKD, available for patients with rapidly progressing disease. Genetic testing can confirm the diagnosis and guide family screening.

5. NSAID-induced nephropathy Chronic NSAID use (ibuprofen, naproxen, diclofenac) reduces prostaglandin-mediated kidney vasodilation, lowering blood flow and filtration. The acute effects are reversible, but chronic heavy use causes structural damage. This connects to our guide on osteoarthritis pain relief, where the NSAID risks for kidney patients are spelled out. Worth correcting a common assumption: acetaminophen (Tylenol) is often recommended as the “safe” alternative, but above 2g/day in CKD it also carries nephrotoxicity risk with chronic use. For chronic kidney disease patients who need pain relief, analgesia should be physician-guided, and topical NSAIDs (diclofenac gel) are generally safer than oral forms.

6. Obesity Obesity drives CKD through three routes: metabolic (raising diabetes and hypertension risk), hemodynamic (higher cardiac output raises kidney filtration pressure), and direct adipokine-mediated inflammation. Even without diabetes or hypertension, obesity on its own causes a distinct form of CKD (obesity-related glomerulopathy). Weight loss, including through GLP-1 medications like semaglutide (covered in our Ozempic guide), reduces kidney hyperfiltration and albuminuria. Our weight loss guide covers the metabolic improvements that come with meaningful weight reduction.

7. Smoking Smoking speeds up CKD progression through endothelial dysfunction and reduced kidney perfusion. National Kidney Foundation data shows that smokers develop chronic kidney disease and reach kidney failure significantly faster than non-smokers at the same baseline eGFR. For patients who smoke, quitting is the single highest-impact lifestyle change for slowing progression.

8. Lupus nephritis Lupus nephritis, kidney involvement in systemic lupus erythematosus, affects 50% to 60% of SLE patients at some point. It needs combined rheumatology-nephrology care and immunosuppressive therapy. A newer FDA-approved agent specifically for lupus nephritis, voclosporin (Lupkynis), was approved in 2021.

Chronic Kidney Disease Symptoms: Why CKD Is Called a Silent Disease

Quick Answer: CKD Stages 1 to 3a are usually symptom-free. Symptoms surface in Stage 3b to 4 as metabolic problems build up: anemia (fatigue, breathlessness on exertion), fluid retention (ankle and foot swelling), electrolyte disturbances (muscle cramps from potassium and calcium imbalances), uremic symptoms (nausea, brain fog, metallic taste), and hard-to-control hypertension. By the time uremic symptoms appear, eGFR is usually below 20 to 25.

Symptoms by stage:

Foamy urine, the overlooked early sign: Protein leaking into urine creates foam (a bit like egg white) that lingers when the stream hits the toilet water. This is one of the few visible early signs of kidney damage. It reflects proteinuria, which a UACR test will pick up. Anyone who notices persistently foamy urine should ask their physician for a UACR.

Anemia of CKD: The kidneys produce erythropoietin (EPO), the hormone that tells bone marrow to make red blood cells. As kidney function falls, EPO production drops, causing a normocytic normochromic anemia. This is a big contributor to the fatigue of chronic kidney disease. Treatment options include erythropoiesis-stimulating agents (ESAs such as darbepoetin alfa and epoetin alfa) for eGFR below 30, or for symptomatic anemia at earlier stages. A newer oral class, HIF-PHI (hypoxia-inducible factor prolyl hydroxylase inhibitors), is also now used for CKD anemia.

Emergency signs that need immediate care:

• A sudden, significant drop in urine output, which may signal acute kidney injury on top of CKD
• Severe shortness of breath with leg swelling, a sign of pulmonary edema from fluid overload
• Chest pain in the chronic kidney disease context, since uremic pericarditis is a Stage 5 complication
• Confusion or altered consciousness, which can reflect uremic encephalopathy

Diagnosing CKD: Blood Tests, Urine Tests, and Imaging

Quick Answer: A CKD diagnosis requires at least two abnormal measurements more than 90 days apart, confirming that the problem is chronic rather than a passing acute finding. The key tests are serum creatinine with a calculated eGFR (blood test), UACR (urine albumin-creatinine ratio on a spot urine sample), and a renal ultrasound. An eGFR below 60 or a UACR above 30 mg/g on two measurements at least 90 days apart confirms CKD under KDIGO criteria.

Key laboratory markers:

• eGFR: Calculated from serum creatinine, age, and sex. This is the primary staging metric. An eGFR of 60 means the kidneys are filtering at about 60% of normal capacity for a healthy young adult.
• Serum creatinine: A waste product of muscle metabolism that rises as the kidneys fail to clear it. A doubling of serum creatinine represents roughly a 50% loss of kidney function.
• UACR (urine albumin-creatinine ratio): Below 30 mg/g is normal; 30 to 300 mg/g is microalbuminuria (early damage); above 300 mg/g is macroalbuminuria (significant damage). Each step up means meaningfully higher progression risk.
• BUN (blood urea nitrogen): Less precise than creatinine, but it reflects protein metabolism and kidney clearance together.
• Serum potassium: Rises in chronic kidney disease as the kidneys struggle to excrete it; hyperkalemia (K+ above 5.5 mEq/L) is a cardiac emergency that needs immediate management.
• Hemoglobin and hematocrit: Track the anemia of CKD.
• Phosphorus and PTH: Both rise in CKD and are managed with phosphate binders and vitamin D analogs to prevent renal bone disease.

Chronic Kidney Disease Treatment: Evidence-Based Approaches

Quick Answer: chronic kidney disease treatment chases three goals at once: slowing progression (blood pressure control, glycemic control, SGLT2 inhibitors, a moderated-protein diet); managing complications (anemia, bone disease, acidosis, electrolyte disturbances); and preparing for renal replacement therapy if progression continues. The biggest shift of the past decade is that SGLT2 inhibitors (dapagliflozin, empagliflozin) are now first-line nephroprotective therapy, the first drug class proven to slow CKD progression independent of blood glucose control.

Renin-angiotensin system (RAS) blockade, first-line for 25 years: ACE inhibitors (lisinopril, ramipril) and ARBs (losartan, valsartan) lower intraglomerular pressure beyond their blood-pressure-lowering effect. They are the cornerstone of CKD treatment, especially for diabetic kidney disease and proteinuric chronic kidney disease, and they cut proteinuria by 30% to 40% independent of blood pressure reduction. One caveat: ACE inhibitors and ARBs can transiently raise creatinine by 10% to 20% when first started in CKD, which comes from the drop in intraglomerular pressure and is expected rather than alarming, and they can cause dangerous hyperkalemia, particularly in Stage 3b to 4. Standard practice is to check potassium and creatinine after starting them.

SGLT2 inhibitors, the breakthrough of the decade: Sodium-glucose cotransporter-2 inhibitors were built as glucose-lowering drugs for type 2 diabetes. Their kidney-protective effects, found unexpectedly in cardiovascular outcomes trials, turned out to be independent of glucose control. The DAPA-CKD trial (Heerspink et al. 2020, New England Journal of Medicine) randomized 4,304 CKD patients, with or without diabetes, to dapagliflozin (Farxiga) or placebo. The result was a 39% relative risk reduction in the composite of sustained eGFR decline of 50% or more, end-stage kidney disease, or death from kidney or cardiovascular causes. The trial was stopped early for overwhelming benefit.

The mechanism: SGLT2 inhibitors reduce glomerular hyperfiltration, the pathological overwork that accelerates chronic kidney disease damage, by constricting the afferent arteriole. That’s the same target as RAS blockade but through a different pathway, so combining an ACE inhibitor or ARB with an SGLT2 inhibitor gives additive kidney protection.

FDA-approved SGLT2 inhibitors for kidney disease:

• Dapagliflozin (Farxiga): approved for CKD in 2021, regardless of diabetes status
• Empagliflozin (Jardiance): approved for CKD and heart failure, similar mechanism
• Canagliflozin (Invokana): approved for chronic kidney disease in type 2 diabetes (CREDENCE trial)

Finerenone (Kerendia): A non-steroidal mineralocorticoid receptor antagonist (nsMRA), approved in 2021 for CKD with type 2 diabetes. It differs from older MRAs like spironolactone with better kidney and cardiovascular specificity and a lower hyperkalemia risk. The FIDELIO-DKD and FIGARO-DKD trials showed meaningful reductions in CKD progression and cardiovascular events.

Blood pressure targets: Current KDIGO 2022 guidelines recommend a target below 120 mmHg systolic (previously 130/80) for chronic kidney disease patients, a significant tightening based on SPRINT trial data. Reaching that target with an ACE inhibitor or ARB plus an SGLT2 inhibitor is now the standard approach.

GLP-1 receptor agonists and kidney protection: Semaglutide (Ozempic and Wegovy) showed kidney-protective effects in the FLOW trial (2024), with a meaningful reduction in kidney disease progression in patients with type 2 diabetes and CKD, from the same drug approved primarily for diabetes and obesity. That creates an overlapping indication with the approaches covered in our Ozempic guide.

The CKD Diet: What to Actually Eat at Each Stage

Quick Answer: The CKD diet isn’t a single protocol. It changes by stage and by individual lab values. The principles that hold across all stages: cut sodium (below 2g/day), keep protein moderate, and stay well hydrated. Potassium and phosphorus restrictions apply mainly to Stages 3b to 5, and only when blood tests show elevated levels, not to every chronic kidney disease patient. Working with a renal dietitian is the standard of care for dietary management from Stage 3 onward.

Stage-by-stage framework:

Stages 1-2 (eGFR 60-89+):

• Main focus: control blood pressure by reducing sodium
• Protein: no restriction supported by current evidence in early CKD
• Potassium and phosphorus: no restriction unless labs are elevated
• A plant-forward diet helps (it lowers acid load and trims protein intake modestly)
• Avoid: high-sodium processed foods, excessive protein supplements, regular NSAID use

Stages 3a-3b (eGFR 30-59):

• Protein: evidence now suggests moderation (0.6 to 0.8 g/kg/day) may slow progression in non-dialysis CKD; severe restriction doesn’t help and risks malnutrition
• Start monitoring potassium and phosphorus; restrict only if elevated
• Potassium may need watching (bananas, potatoes, tomatoes), but again only restrict if blood K+ is high
• Limit phosphorus-heavy foods, especially processed foods with phosphate additives, which are absorbed far more completely than the organic phosphorus in whole foods
• High-protein snacks popular in fitness circles become a problem here. Our guide to high-protein snacks covers how to adapt those choices for a kidney-health context

Stages 4-5 (eGFR <30):

• Full renal dietitian management required
• Strict potassium restriction (typically below 2,000mg/day) when hyperkalemia is present
• Strict phosphorus restriction plus phosphate binders as prescribed
• Fluid restriction if fluid retention is present
• Protein: maintained or increased on dialysis, since dialysis removes protein, so dialysis patients need more of it, the opposite of pre-dialysis chronic kidney disease

Key nutrient adjustments with CKD:

• Sodium: The most important restriction at every stage. Target below 2,000mg/day (against an average American intake of about 3,400mg/day). Read labels, since most processed foods, canned goods, and restaurant meals run high.
• Potassium: Restrict only when blood K+ is above 5.0 mEq/L, not for every CKD patient. High-potassium foods to cut back on if labs say so: bananas, potatoes, oranges, tomatoes, avocados, dairy.
• Phosphorus: Phosphate additives in processed foods (listed as PHOS on labels) are 90% to 100% absorbed, while natural phosphorus from whole foods is 40% to 60% absorbed. Prioritize avoiding processed-food phosphates over restricting the naturally occurring phosphorus in beans and dairy.
• Protein: High-protein diets raise kidney filtration demand. But very low-protein diets in pre-dialysis chronic kidney disease can cause malnutrition, so current evidence supports moderate protein (0.6 to 0.8 g/kg/day) in Stage 3 to 4. Protein needs rise again once on dialysis.

Managing CKD Long-Term: Monitoring, Complications, and Quality of Life

Quick Answer: Long-term CKD management rests on four pillars: regular monitoring (eGFR, UACR, and electrolytes every 3 to 12 months depending on stage); treating cardiovascular risk (Stage 3 patients carry a higher absolute risk of cardiovascular death than of kidney failure, and lipid management and aspirin use need physician guidance); managing complications (anemia, bone disease, acidosis); and planning renal replacement therapy once Stage 4 to 5 arrives. Median 5-year survival after starting dialysis is about 35%, which is why transplant is the preferred option wherever possible.

Cardiovascular risk, the most important complication: Stage 3 CKD doubles cardiovascular mortality risk, independent of other factors. CKD is now treated as a coronary artery disease equivalent for cardiovascular risk stratification. Statins reduce cardiovascular events in chronic kidney disease patients (the SHARP trial). Blood pressure control, SGLT2 inhibitors, and GLP-1 agonists address cardiovascular and kidney risk at the same time.

Monitoring schedule (KDIGO):

Dialysis and transplant: Dialysis starts when eGFR falls below 10 to 15 and uremic symptoms or complications can’t be managed with medication. The two forms are hemodialysis (three times a week, usually in a dialysis center, 3 to 4 hours per session) and peritoneal dialysis (daily exchanges done at home). A kidney transplant offers the best outcomes, with 5-year graft survival above 85% for living-donor transplants versus about 35% 5-year survival on dialysis. Listing for transplant early, before dialysis starts, is linked to better outcomes, and a pre-emptive transplant (before dialysis is needed) is the ideal path when a compatible donor is available.

Frequently Asked Questions About Chronic Kidney Disease

This article is for informational purposes only and does not constitute medical advice or replace the guidance of a nephrologist or other qualified healthcare provider. Chronic kidney disease requires individualized medical management. Dietary restrictions (particularly potassium and phosphorus limits), medication adjustments, and treatment decisions must be guided by your specific eGFR, UACR, and blood chemistry results, not general-audience guidelines. If you have or suspect kidney disease, please consult a physician and request the appropriate laboratory screening.

Mimo Karam

Mimo Karam is the founder and writer at LifestyleMine. She writes about daily habits, nutrition, sleep, and emotional wellness, turning research into practical advice for people who want to live healthier without making it complicated.