Chronic Kidney Disease (CKD) Guide: A Doctor's 2025 Guide to Stages, Diet & Treatment

Introduction

"My doctor said my kidneys aren't working as well as they should. What does that mean?"

I have this conversation several times a week in my clinic. Chronic kidney disease (CKD) is often discovered incidentally – a routine blood test shows elevated creatinine, and suddenly a patient is facing a diagnosis they never expected.

The truth is, CKD is incredibly common. An estimated 37 million American adults have it, and most don't know it. The good news? With early detection and proper management, progression can be slowed significantly.

In this guide, I'll explain:

• What kidneys do and why they matter
• The stages of CKD and what they mean
• Common causes (especially diabetes and hypertension)
• Symptoms to watch for (and why early stages have none)
• How CKD is diagnosed (eGFR, urine albumin)
• Treatment options by stage
• Dietary changes that protect kidneys
• When dialysis or transplant is needed

What Do Kidneys Do?

Your kidneys are two fist-sized organs located below your rib cage, one on each side of your spine. Despite their small size, they perform vital functions:

What Is Chronic Kidney Disease?

Chronic kidney disease means your kidneys are damaged and can't filter blood as well as they should. The damage happens gradually over months or years.

Key measurements:

• eGFR (estimated Glomerular Filtration Rate): How well your kidneys filter waste. Calculated from blood creatinine, age, gender, and race. Normal is >90 mL/min/1.73m².
• Urine albumin-to-creatinine ratio (UACR): Measures protein (albumin) in urine. Protein leakage indicates kidney damage.

The 5 Stages of CKD

Common Causes of CKD

Risk Factors

• Diabetes: The #1 risk factor
• High blood pressure: #2 risk factor
• Heart disease: Closely linked
• Family history: Kidney disease, diabetes, hypertension
• Age: >60 years
• Race: African American, Hispanic, Native American, Asian American
• Obesity: Increases diabetes and hypertension risk
• Smoking: Damages blood vessels

Symptoms: Why Early CKD Is Silent

In early stages (1-3), CKD typically has no symptoms at all. The kidneys are remarkably resilient and compensate until function is significantly reduced.

Symptoms as CKD Progresses (Stages 4-5):

Diagnosis: How CKD Is Detected

Blood Tests

• Creatinine: Waste product; high levels = poor filtration
• eGFR: Calculated from creatinine – the key number for staging
• BUN (Blood Urea Nitrogen): Another waste product
• Electrolytes: Sodium, potassium, calcium, phosphorus

Urine Tests

• Urinalysis: Checks for blood, protein, infection
• Albumin-to-creatinine ratio (UACR): Measures protein leakage
• 24-hour urine collection: Sometimes needed for precise measurement

Imaging

• Ultrasound: Checks kidney size, structure, cysts, blockages
• CT scan: More detailed, sometimes with contrast (caution in CKD)

Biopsy (rarely needed)

• Needle sample of kidney tissue to determine cause of damage
• Usually for unexplained rapid decline or suspected glomerulonephritis

Treatment by Stage

Stages 1-2 (Early CKD)

• Goal: Slow progression, treat underlying cause
• Blood pressure control: ACE inhibitors or ARBs (protect kidneys)
• Blood sugar control: If diabetic, tight control
• Lifestyle: Healthy diet, exercise, stop smoking
• Avoid NSAIDs: Ibuprofen, naproxen – can worsen kidney damage

Stage 3 (Moderate CKD)

• All of the above, plus:
• Monitor for complications: Anemia, bone disease, electrolyte imbalances
• Dietary changes: May need to limit protein, sodium, potassium, phosphorus
• Medication adjustments: Many drugs need dose adjustments based on eGFR
• Vaccinations: Hepatitis B, flu, pneumonia – infections more dangerous in CKD

Stage 4 (Severe CKD)

• Intensive management of complications:
• Anemia: May need iron supplements or erythropoiesis-stimulating agents (ESA)
• Bone disease: Vitamin D, phosphate binders
• Acidosis: Sodium bicarbonate to correct pH
• Nutrition counseling: Strict dietary restrictions
• Prepare for kidney replacement therapy: Discuss dialysis and transplant options
• Vascular access planning: Fistula placement (takes months to mature)

Stage 5 (Kidney Failure)

• Dialysis or transplant needed to survive
• Hemodialysis: Blood filtered by machine, usually 3x/week at center
• Peritoneal dialysis: Done at home using abdominal lining as filter
• Kidney transplant: Best option for eligible patients – living or deceased donor
• Conservative management: For those who choose not to pursue dialysis, focus on comfort

Medications That Protect Kidneys

ACE Inhibitors and ARBs

Lisinopril, losartan, and similar drugs lower blood pressure and reduce protein leakage. They protect kidneys even in people with normal blood pressure.

SGLT2 Inhibitors

Jardiance, Farxiga – originally diabetes drugs, now proven to slow CKD progression even in non-diabetics.

Finerenone

Newer medication for CKD with type 2 diabetes; reduces progression and cardiovascular events.

Medications to Avoid or Use Cautiously

• NSAIDs: Ibuprofen, naproxen, celecoxib – can worsen kidney function
• Metformin: Safe until eGFR <30, but then contraindicated
• Contrast dye: For CT scans – can cause acute kidney injury in advanced CKD
• Certain antibiotics: Gentamicin, vancomycin – require monitoring

Diet for CKD: What to Eat (and Avoid)

Diet becomes increasingly important as CKD progresses. Recommendations vary by stage, so work with a renal dietitian.

Sodium

Limit: <2,300 mg/day (ideally <1,500 mg)

Why: Controls blood pressure and fluid retention

Avoid: Processed foods, canned soups, fast food, salty snacks

Protein

Not too much: Excess protein stresses kidneys

Not too little: Can cause malnutrition

Goal: 0.6-0.8 g/kg/day in advanced CKD (individualized)

Sources: High-quality protein (eggs, fish, poultry) in controlled amounts

Potassium

Monitor if eGFR <30 or potassium high

High-potassium foods to limit: Bananas, oranges, potatoes, tomatoes, avocados, dried fruits

Lower-potassium options: Apples, berries, grapes, pineapple, green beans

Phosphorus

Limit when eGFR <30: High phosphorus damages bones and blood vessels

High-phosphorus foods: Dairy, nuts, seeds, beans, colas, processed foods

Phosphate binders: Medications taken with meals to block phosphorus absorption

Fluids

May need to limit in advanced CKD: Especially if swelling or shortness of breath

Goal: Often urine output + 500 mL (individualized)

Frequently Asked Questions

When to See a Doctor

• If you have diabetes or hypertension and haven't had kidney function checked in the last year
• Family history of kidney disease
• Swelling in feet, ankles, or face
• Foamy urine (sign of protein)
• Blood in urine
• Unexplained fatigue, nausea, or itching
• eGFR <60 or protein in urine on any test

Doctor's Bottom Line

Chronic kidney disease is common, silent, and serious – but manageable. The keys to protecting your kidneys:

1. Know your numbers. eGFR and UACR – ask for them if you're at risk.
2. Control blood pressure. ACE inhibitors/ARBs protect kidneys even without high BP.
3. Manage diabetes tightly. A1c goal <7% (individualized).
4. Avoid nephrotoxins. NSAIDs, excess protein, unregulated supplements.
5. Follow dietary guidelines. Especially sodium, potassium, phosphorus in advanced stages.
6. Don't delay specialist care. Early nephrology referral improves outcomes.

With proper management, many people with CKD live full, active lives for decades. The key is early detection and consistent care.

References

• KDIGO 2024 Clinical Practice Guideline for the Evaluation and Management of Chronic Kidney Disease. Kidney Int. 2024;105(4S):S1-S117.
• Centers for Disease Control and Prevention. Chronic Kidney Disease Surveillance System. 2024.
• American Diabetes Association. Standards of Medical Care in Diabetes—2025. Diabetes Care. 2025;48(Suppl 1).
• Whelton PK, et al. 2017 ACC/AHA Hypertension Guideline. Hypertension. 2018.