Understanding Chronic Kidney Disease (CKD)

Introduction: Why Your Kidneys Matter More Than You Think

As a nephrologist — a physician who specializes in kidney disease — I have spent my career helping patients understand, manage, and slow the progression of kidney disease. One of the most important messages I share with every patient is this: chronic kidney disease often has no symptoms until it is already quite advanced. That is why education, early detection, and proactive management are not just helpful — they are life-changing.

This guide is designed to give you a thorough, honest, and medically accurate understanding of chronic kidney disease (CKD): what it is, how it is diagnosed, who is at risk, what you can do about it, and when to seek specialized care. Whether you have been recently diagnosed, have risk factors like diabetes or high blood pressure, or simply want to protect your long-term health, this resource is for you.

What Do the Kidneys Actually Do?

Your kidneys are two bean-shaped organs, each roughly the size of a fist, located on either side of your spine just below your rib cage. Despite their small size, they perform an extraordinary number of vital functions:

• Filter approximately 200 liters of blood every single day, removing waste products and excess fluid as urine

• Regulate blood pressure through the renin-angiotensin-aldosterone system (RAAS)

• Balance electrolytes such as sodium, potassium, calcium, and phosphorus

• Produce erythropoietin (EPO), the hormone that signals your bone marrow to make red blood cells

• Activate vitamin D, which is essential for strong bones and immune function

• Maintain acid-base balance to keep your body's pH in a healthy range

• Clear medications, toxins, and metabolic byproducts from your system

  
  

When the kidneys lose function — even gradually — every one of these processes is affected. This is why CKD is not just a kidney problem; it has widespread effects on cardiovascular health, bone density, energy levels, brain function, and overall quality of life.

What Is Chronic Kidney Disease (CKD)?

Chronic kidney disease is defined as abnormalities of kidney structure or function, present for more than three months, with implications for health. The key word is chronic — meaning long-lasting and persistent, not temporary or reversible.

CKD affects an estimated 37 million adults in the United States — about 1 in 7 adults — yet the vast majority do not know they have it. Globally, CKD affects over 800 million people and is among the fastest-growing causes of death worldwide.

CKD is diagnosed when one or both of the following markers are present for at least three months:

• An estimated glomerular filtration rate (eGFR) below 60 mL/min/1.73m²

• Evidence of kidney damage, such as protein in the urine (proteinuria/albuminuria), structural abnormalities on imaging, or pathological changes on biopsy

The Stages of CKD: Understanding How Kidney Function Is Classified

CKD is classified into five stages (G1–G5) based primarily on eGFR, and further categorized by the degree of albuminuria (protein in the urine). Understanding your stage helps your care team tailor treatment to your specific needs.

Stage	eGFR (mL/min/1.73m²)	Description	What This Means for You
G1	≥ 90	Normal or High	Kidney damage present but function is normal. Identify and treat the cause; monitor closely.
G2	60–89	Mildly Decreased	Slightly reduced function, usually no symptoms. Lifestyle changes and BP control are key.
G3a	45–59	Mildly to Moderately Decreased	Closer monitoring needed. Watch for anemia and early bone mineral changes.
G3b	30–44	Moderately to Severely Decreased	Higher cardiovascular risk. Nephrology referral strongly recommended.
G4	15–29	Severely Decreased	Begin planning for kidney replacement therapy. Discuss dialysis and transplant options.
G5	< 15	Kidney Failure (ESKD)	Dialysis or kidney transplant is required for survival.

Important: Stage alone does not tell the whole story. Two patients at the same eGFR may have very different prognoses depending on the amount of protein in their urine, their underlying cause of CKD, and their other medical conditions. This is why individualized care with a nephrologist matters.

What Causes CKD? Common and Less Common Causes

The Most Common Causes

Diabetic Kidney Disease (Diabetic Nephropathy): Diabetes is the single leading cause of CKD and end-stage kidney disease (ESKD) in the United States, responsible for approximately 38% of new dialysis cases. Chronically elevated blood sugar damages the delicate filtering units of the kidney (glomeruli). Early diabetic kidney disease is often silent — detectable only by urine protein testing — which is why annual screening is essential for all patients with diabetes.

Hypertensive Nephrosclerosis: High blood pressure is the second most common cause of CKD. Over time, uncontrolled hypertension causes the small blood vessels within the kidney to thicken and stiffen, reducing blood flow and filtration capacity. The relationship is bidirectional — CKD also worsens hypertension, creating a damaging cycle.

IgA Nephropathy (Berger's Disease): The most common primary glomerular disease worldwide, IgA nephropathy occurs when IgA antibodies accumulate in the kidney's filtering units, triggering inflammation. Recent years have brought exciting new targeted treatments, making early diagnosis increasingly important.

Autoimmune Diseases: Conditions such as lupus (systemic lupus erythematosus), ANCA-associated vasculitis, and anti-GBM disease can attack the kidneys directly, causing rapidly progressive damage if not identified and treated promptly.

Polycystic Kidney Disease (PKD): A genetic condition in which fluid-filled cysts develop in both kidneys, gradually enlarging them and reducing functional tissue. Autosomal dominant PKD (ADPKD) is the most common inherited kidney disease, affecting approximately 1 in 400 to 1 in 1,000 people.

Other Important Causes

• Recurrent or chronic kidney infections (pyelonephritis)

• Kidney stones causing obstruction

• Focal segmental glomerulosclerosis (FSGS) and membranous nephropathy

• Alport syndrome (hereditary nephritis)

• Medication-related nephrotoxicity (NSAIDs, certain antibiotics, contrast dye)

• Obstructive uropathy (enlarged prostate, structural abnormalities)

Who Is at Risk for CKD?

Knowing your risk factors empowers you to take action before kidney function declines.

Risk Category	Examples
Medical Conditions	Diabetes, high blood pressure, heart disease, obesity, recurrent kidney infections, kidney stones, lupus, vasculitis, IgA nephropathy, polycystic kidney disease
Demographics	Age 60 or older; African American, Hispanic, Native American, or Asian American heritage
Family History	First-degree relatives with kidney disease, dialysis, or kidney transplant
Medications & Exposures	Long-term NSAIDs (ibuprofen, naproxen), certain antibiotics, IV contrast dye, nephrotoxic herbal supplements
Lifestyle Factors	Smoking, chronic dehydration, high-sodium or high-protein diets, obesity

 Check your BMI and CKD risk →

Are You at Risk? These Two Tests Can Tell You.

If any of the above apply to you, ask your healthcare provider for:

1. Serum creatinine and calculated eGFR (blood test)

2. Urine albumin-to-creatinine ratio (uACR) (urine test)

3. Blood pressure measurement

Signs and Symptoms: Why CKD Is Called the "Silent Disease"

One of the greatest challenges in CKD care is its silence. The kidneys have tremendous reserve capacity — you can lose up to 60–70% of kidney function before experiencing noticeable symptoms. This is why so many patients are surprised to learn they have significant kidney disease.

Early Stages (G1–G3): Often No Symptoms

In early to moderate CKD, most people feel entirely normal. CKD is often discovered incidentally during routine blood or urine testing. Occasionally, patients may notice:

• Foamy or bubbly urine (suggesting protein loss)

• Blood in the urine (hematuria) — sometimes only visible under a microscope

• Slightly elevated blood pressure

  
  

Later Stages (G4–G5): Uremic Symptoms Emerge

As kidney function declines further, waste product buildup (uremia) causes symptoms that can profoundly affect quality of life:

• Fatigue and weakness — often due to anemia from reduced erythropoietin production

• Swelling (edema) in the feet, ankles, legs, or around the eyes from fluid retention

• Shortness of breath from fluid in the lungs or anemia

• Poor appetite, nausea, vomiting from uremic toxin buildup

• Difficulty concentrating or mental fogginess ("uremic encephalopathy")

• Muscle cramps, particularly at night, from electrolyte imbalances

• Dry, itchy skin (uremic pruritus)

• Decreased urination or changes in urine output

• Bone pain or fractures from disordered mineral metabolism

• Metallic taste in the mouth or ammonia-like breath

If you are experiencing any of these symptoms — particularly with known risk factors — please seek medical evaluation promptly.

How Is CKD Diagnosed? The Tests You Need to Know

1. Estimated Glomerular Filtration Rate (eGFR)

   
   

   The eGFR is the cornerstone of CKD diagnosis and staging. It estimates how much blood your kidneys filter per minute. It is calculated from your serum creatinine, age, and sex. A single low eGFR is not sufficient for diagnosis — abnormalities must persist for at least 3 months to confirm CKD (ruling out acute kidney injury).

   
   

   Normal eGFR: Generally 60 or above for most adults, though it naturally declines slightly with aging — the average person loses about 1 mL/min per year after age 40.

   
   

   Calculate your eGFR →

   
   

2. Urine Albumin-to-Creatinine Ratio (uACR)

   
   

   Albumin is a protein that healthy kidneys prevent from leaking into urine. When filters are damaged, albumin leaks out — called albuminuria or proteinuria. The uACR quantifies this leak. Even with a normal eGFR, significant albuminuria is diagnostic of CKD and is one of the strongest predictors of progression and cardiovascular risk.

Albuminuria Categories

A1 (Normal to mildly increased): uACR < 30 mg/g

A2 (Moderately increased): uACR 30–300 mg/g

A3 (Severely increased): uACR > 300 mg/g

  Check your kidney failure risk score →

3. Additional Diagnostic Tests

Depending on clinical context, your nephrologist may order:

• Complete metabolic panel — sodium, potassium, bicarbonate, phosphorus, calcium, BUN, creatinine

• Complete blood count (CBC) — to assess for anemia

• PTH and vitamin D levels — for bone health assessment

• Renal ultrasound — to evaluate kidney size, structure, and rule out obstruction

• Autoimmune workup — ANA, ANCA, complement levels, anti-GBM antibodies if glomerulonephritis is suspected

• Kidney biopsy — when the cause is unclear or a treatable diagnosis needs confirmation

Complications of CKD: What Happens When Kidneys Fail Gradually

Cardiovascular Disease

Cardiovascular disease is the leading cause of death in CKD patients — more patients die from heart disease than progress to dialysis. CKD accelerates atherosclerosis, causes left ventricular hypertrophy, promotes inflammation, and disrupts fluid and electrolyte balance. Every reduction in eGFR category is associated with increasing cardiovascular risk.

Anemia of CKD

Reduced erythropoietin production leads to anemia, causing fatigue, reduced exercise tolerance, impaired cognition, and worsening cardiac strain. Management includes iron supplementation and erythropoiesis-stimulating agents (ESAs).

CKD-Mineral and Bone Disorder (CKD-MBD)

As eGFR declines, phosphorus accumulates, active vitamin D production falls, and PTH rises — secondary hyperparathyroidism. Left untreated, CKD-MBD causes weakened bones, vascular calcifications, and increased fracture risk.

Metabolic Acidosis

Failing kidneys cannot adequately excrete acid, leading to low blood bicarbonate (metabolic acidosis). This accelerates muscle wasting, worsens bone disease, and independently promotes CKD progression. Oral sodium bicarbonate is an effective, inexpensive treatment.

Hyperkalemia

As CKD progresses, elevated blood potassium (hyperkalemia) becomes a significant risk — it can cause dangerous heart arrhythmias. Management includes dietary potassium restriction and newer potassium binders such as patiromer and sodium zirconium cyclosilicate.

Fluid Overload and Hypertension

Impaired sodium and water excretion leads to fluid retention, worsening hypertension and potentially causing heart failure. Diuretics and strict sodium restriction are central to management.

How Is CKD Managed? A Comprehensive Approach

1. Blood Pressure Control

   Target blood pressure in CKD is generally below 120–130/80 mmHg, particularly with significant proteinuria. Cornerstone medications include:

   • ACE inhibitors (e.g., lisinopril, ramipril) — reduce intraglomerular pressure and proteinuria

   • ARBs (e.g., losartan, irbesartan) — equivalent to ACE inhibitors, often better tolerated

   • These agents protect kidney function independently of their blood pressure-lowering effect

     
     

2. Blood Sugar Control in Diabetic CKD

   Tight glycemic control slows diabetic kidney disease progression. Beyond traditional medications, newer drug classes have shown remarkable kidney-protective effects:

   • SGLT2 inhibitors (empagliflozin, dapagliflozin, canagliflozin) — now indicated for CKD even in patients without diabetes; reduce kidney disease progression, hospitalization for heart failure, and cardiovascular death

   • GLP-1 receptor agonists (semaglutide, liraglutide) — reduce albuminuria and support weight loss

   
   

3. Dietary Modifications

   Nutrition is a powerful tool in CKD management. Key principles include:

   • Sodium restriction (2,000 mg/day or less) — reduces blood pressure and fluid retention

   • Protein moderation (0.6–0.8 g/kg/day for non-dialysis CKD) — reduces uremic waste

     Calculate your daily protein goal →

   • Potassium management — individualized based on lab values; NOT all CKD patients need restriction

   • Phosphorus limitation — avoid processed foods high in phosphate additives

   • Plant-forward diet — emerging evidence supports plant-based proteins and Mediterranean or DASH dietary patterns in CKD

     Try our plant-forward nutrition planner →

   
   

   Important: Dietary needs in CKD are highly individualized and change with disease stage. Please consult a registered dietitian with CKD expertise rather than following generic kidney diet advice online.

   
   

4. Avoiding Kidney-Toxic Exposures

   • NSAIDs (ibuprofen, naproxen) — reduce blood flow to the kidneys; use acetaminophen for pain instead, with guidance

   • IV contrast dye — notify your radiologist; pre-hydration protocols may be needed

   • Nephrotoxic antibiotics — aminoglycosides, vancomycin; always disclose your CKD to prescribers

   • Herbal supplements — many, including aristolochic acid-containing herbs and certain Chinese herbal remedies, are directly nephrotoxic

   
   

5. Managing Complications

   • Anemia: Iron studies, ESAs, and newer HIF-PHI agents (daprodustat)

   • CKD-MBD: Phosphate binders, active vitamin D analogs, calcimimetics

   • Metabolic acidosis: Oral sodium bicarbonate supplementation

   • Hyperkalemia: Dietary restriction, patiromer or sodium zirconium cyclosilicate

   • Fluid overload: Loop diuretics (furosemide), sodium and fluid restriction

   
   

6. Cardiovascular Risk Reduction

   • Statin therapy — most CKD patients benefit

   • SGLT2 inhibitors — dual kidney and heart protection

   • Finerenone (Kerendia) — non-steroidal MRA approved to reduce CKD progression and cardiovascular events in diabetic CKD

   
   

7. Preparing for Kidney Replacement Therapy (When Needed)

   For patients approaching Stage 5, planning ahead makes an enormous difference in outcomes. Options include:

   
   

   • Hemodialysis — performed in a dialysis center or at home, typically 3 times per week

     Do I need dialysis? Read the blog to learn more.

   • Peritoneal dialysis — uses the abdominal lining as a filter; performed at home, offering greater flexibility

   • Kidney transplantation — the preferred treatment for eligible patients; pre-emptive transplant before dialysis starts yields the best outcomes

   
   

   I strongly advocate for early referral to a transplant center for appropriate patients, and for thorough, unhurried education about all options so patients can make choices aligned with their values and lifestyle.

When Should You See a Nephrologist?

Your primary care provider can manage early CKD, but there are specific circumstances where evaluation by a nephrologist (kidney specialist) is essential:

Indications for Nephrology Referral

1. eGFR < 60 mL/min/1.73m² (Stage G3a or below)

2. Rapidly declining eGFR (loss of > 5 mL/min per year)

3. Significantly elevated uACR > 300 mg/g (macroalbuminuria)

4. Persistent blood in the urine (hematuria) without urological explanation

5. Difficult-to-control hypertension despite multiple medications

6. Persistent electrolyte or acid-base abnormalities

7. CKD in young patients or with unusual features suggesting a hereditary or glomerular cause

Exciting Advances in CKD Treatment: Hope on the Horizon

CKD care has been transformed over the past decade, and the pace of progress is accelerating. Here are the most important recent developments:

• SGLT2 inhibitors: Dapagliflozin and empagliflozin are now FDA-approved for CKD regardless of diabetes status, with landmark trials showing 30–40% reductions in CKD progression

• Finerenone (Kerendia): A novel non-steroidal mineralocorticoid receptor antagonist approved for diabetic CKD

• Sparsentan (Filspari): A dual endothelin-angiotensin receptor antagonist; FDA-approved for IgA nephropathy to reduce proteinuria and slow progression

• Tarpeyo (budesonide): A targeted-release oral corticosteroid FDA-approved for IgA nephropathy; delivers anti-inflammatory therapy directly to the gut-kidney axis

• APRIL/BAFF inhibitors for IgA nephropathy: Iptacopan targets the complement pathway; sibeprenlimab (anti-APRIL) and zigakibart (anti-BAFF) are in late-stage trials with FDA Breakthrough Therapy designation — watch for approvals

• Tavneos (avacopan): FDA-approved complement C5a receptor inhibitor for ANCA-associated vasculitis; replaces high-dose steroids in remission induction and reduces organ damage

• HIF-PHI agents (daprodustat): Oral agents for anemia of CKD

• Patiromer and sodium zirconium cyclosilicate: Novel potassium binders enabling patients to stay on RAAS-blocking medications

• Implantable artificial kidneys: The Kidney Project at UCSF and other programs are developing bioartificial kidneys — early-stage but promising

If you have been told there is nothing more to do for your kidney disease, I encourage you to seek a second opinion. The landscape of treatment has changed dramatically.

CKD Risk Heat Map: Are You in a High-Risk Zone?

Taking Charge of Your Kidney Health: Patient Advocacy Tips

As a patient, you are the most important member of your healthcare team. Here is how to advocate for yourself:

• Know your numbers: Ask for your eGFR and uACR at every relevant appointment and track trends over time

• Bring a complete medication and supplement list to every visit

• Do not skip nephrology follow-up appointments — CKD requires consistent monitoring

• Ask questions: What is causing my CKD? What is my goal eGFR trend? Do I need a kidney biopsy?

• Consider a renal dietitian consultation — dietary management in CKD is nuanced and personalized

• Connect with support organizations: The American Kidney Fund and the National Kidney Foundation offer resources, financial assistance, and peer support

• Plan ahead: If your CKD is advanced, start conversations about kidney replacement therapy early — ideally 12–18 months before you might need it

• Address mental health: Depression and anxiety are common and underrecognized in CKD; ask for behavioral health referrals

The Bottom Line: Early Action Changes Everything

Key Takeaways for You and Your Family

1. CKD affects 1 in 7 American adults, but most don't know they have it.

2. Early CKD is silent — you cannot feel it. Regular screening is the only way to find it early.

3. CKD cannot usually be cured, but its progression can often be significantly slowed — sometimes for decades — with the right treatment.

4. New medications like SGLT2 inhibitors and finerenone are changing the trajectory of CKD care.

5. Blood pressure control, blood sugar management, and nephrotoxin avoidance are the pillars of prevention.

6. If you or a loved one has risk factors for CKD, talk to your doctor about kidney screening today.

As a nephrologist, I believe that patients who understand their disease are empowered to fight it. The goal is not just to manage kidney disease, but to partner with you — giving you the knowledge, tools, and compassionate expert care to protect your kidneys for as long as possible.

If you have questions about your kidney health or would like to schedule an evaluation, please reach out.

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References

This article is written for patient education and is based on current evidence-based guidelines and peer-reviewed literature. Key sources include:

1. Kidney Disease: Improving Global Outcomes (KDIGO) CKD Work Group. KDIGO 2024 Clinical Practice Guideline for the Evaluation and Management of Chronic Kidney Disease. Kidney Int. 2024;105(4S):S117–S314.

2. Centers for Disease Control and Prevention (CDC). Chronic Kidney Disease in the United States, 2023. Atlanta, GA: US Department of Health and Human Services, CDC; 2023.

3. Heerspink HJL, Stefansson BV, Correa-Rotter R, et al. Dapagliflozin in Patients with Chronic Kidney Disease. N Engl J Med. 2020;383(15):1436–1446.

4. Perkovic V, Jardine MJ, Neal B, et al. Canagliflozin and Renal Outcomes in Type 2 Diabetes and Nephropathy. N Engl J Med. 2019;380(24):2295–2306.

5. Bakris GL, Agarwal R, Anker SD, et al. Effect of Finerenone on Chronic Kidney Disease Outcomes in Type 2 Diabetes. N Engl J Med. 2020;383(23):2219–2229.

6. Kalantar-Zadeh K, Jafar TH, Nitsch D, Neuen BL, Perkovic V. Chronic kidney disease. Lancet. 2021;398(10302):786–802.

7. National Kidney Foundation. KDOQI Clinical Practice Guidelines for Chronic Kidney Disease. Am J Kidney Dis. 2002;39(2 Suppl 1):S1–S266. (Updated guidance at kidney.org)

8. Levey AS, Coresh J. Chronic kidney disease. Lancet. 2012;379(9811):165–180.

9. Go AS, Chertow GM, Fan D, McCulloch CE, Hsu CY. Chronic kidney disease and the risks of death, cardiovascular events, and hospitalization. N Engl J Med. 2004;351(13):1296–1305.

10. Thurlow JS, Joshi M, Yan G, et al. Global Epidemiology of End-Stage Kidney Disease and Disparities in Kidney Replacement Therapy. Am J Nephrol. 2021;52(2):98–107.

11. United States Renal Data System. 2023 USRDS Annual Data Report. National Institutes of Health, NIDDK, Bethesda, MD, 2023.

12. Cheung AK, Chang TI, Cushman WC, et al. KDIGO 2021 Clinical Practice Guideline for the Management of Blood Pressure in Chronic Kidney Disease. Kidney Int. 2021;99(3S):S1–S87.

This article is for educational purposes only and does not constitute medical advice. Please consult with a qualified healthcare provider for personalized medical guidance.