A common conversation I have with my patients involves the implications of the eGFR, or estimated glomerular filtration rate. This value is on every chemistry panel we order and is often found to be diminished, frequently unexpectedly, on blood work. This can be anxiety provoking, and is certainly confusing, inasmuch as this dysfunction is usually asymptomatic and has significant health implications.

Chronic Kidney Disease (CKD) is a progressive condition affecting millions worldwide. This guide aims to demystify CKD, its stages, and evidence-based strategies for management.

The Stages of CKD and the Importance of eGFR

Chronic Kidney Disease is classified into five stages based on the estimated Glomerular Filtration Rate (eGFR), a measure of how well the kidneys filter waste from the blood. The eGFR is calculated using serum creatinine levels, age, sex, and race.

CKD stages:

1. Stage 1: Kidney damage with normal or increased GFR (>90 mL/min/1.73 m²)
2. Stage 2: Mild reduction in GFR (60-89 mL/min/1.73 m²)
3. Stage 3a: Moderate reduction in GFR (45-59 mL/min/1.73 m²)
4. Stage 3b: Moderate reduction in GFR (30-44 mL/min/1.73 m²)
5. Stage 4: Severe reduction in GFR (15-29 mL/min/1.73 m²)
6. Stage 5: Kidney failure (GFR <15 mL/min/1.73 m² or dialysis)

Understanding these stages is crucial for diagnosis and treatment planning. As the disease progresses, the risk of complications increases, making early detection and intervention vital.

Preserving Kidney Function: Evidence-Based Strategies

Lifestyle Modifications

1. Blood Pressure Control: Maintaining optimal blood pressure is crucial in slowing CKD progression.
2. Glycemic Control: For diabetic patients, tight glycemic (blood sugar) control can significantly reduce the risk of kidney damage.
3. Dietary Changes: A low-sodium, low-protein diet can help reduce the workload on the kidneys.
4. Exercise: Regular physical activity can improve overall health and help manage comorbidities like hypertension and diabetes.

Pharmacological Interventions: medicines to treat CKD

Several medications have shown promise in preserving kidney function:

1. ACE Inhibitors and ARBs: These medications help control blood pressure and reduce proteinuria, slowing CKD progression.
2. SGLT2 Inhibitors: Originally developed for diabetes, these drugs have shown remarkable renoprotective effects in both diabetic and non-diabetic CKD patients.
3. Mineralocorticoid Receptor Antagonists (MRAs): Drugs like spironolactone and eplerenone can help manage resistant hypertension and reduce proteinuria.
4. Finerenone: A non-steroidal MRA that has shown promising results in reducing both renal and cardiovascular outcomes in patients with diabetic kidney disease.

Dietary Considerations for Advanced CKD

As kidney function declines, dietary restrictions become more crucial:

1. Protein Intake: Moderate protein consumption is recommended. Too much protein can overwork the kidneys, while too little may lead to malnutrition.
2. Sodium Restriction: Limiting sodium (salt) helps control blood pressure and reduces fluid buildup.
3. Potassium Management: Foods high in potassium (e.g., oranges, potatoes, tomatoes) should be limited as excess potassium can cause heart problems.
4. Phosphorus Control: Reduce intake of foods high in phosphorus (meat, dairy, beans, nuts, whole-grain bread) to prevent bone weakening and blood vessel damage.
5. Fluid Restriction: In advanced stages, limiting fluid intake becomes necessary to prevent fluid buildup.

Foods to Focus On:

• Fruits: berries, grapes, apples, plums
• Vegetables: cauliflower, onions, eggplant, turnips
• Proteins: lean meats (poultry, fish), eggs, unsalted seafood
• Carbohydrates: white bread, unsalted crackers, pasta

Things to Avoid

1. Artificial Sweeteners: While the relationship between artificial sweeteners and CKD risk is not definitively established, some studies suggest a potential link. Caution is advised.
2. Proton Pump Inhibitors (PPIs): Long-term use of PPIs has been associated with an increased risk of CKD. If prescribed, discuss the risks and benefits with your healthcare provider.
3. Herbal Supplements: Many herbal supplements can be harmful to kidney function. Avoid supplements like astragalus, horsetail, licorice root, and others without consulting a healthcare professional.
4. High-Potassium Foods: In advanced stages, limit intake of high-potassium foods like bananas, oranges, and potatoes.
5. Phosphate-Rich Foods: Reduce consumption of dairy products, nuts, and cola drinks.
6. Excessive Protein: Especially from red meat sources.
7. Alcohol: Limit or avoid alcohol consumption as it can interfere with kidney function and medications.
8. Raw or Unpasteurized Foods: These may increase the risk of foodborne illnesses in immunocompromised individuals.
9. Nephrotoxic Medications: NSAIDs, certain antibiotics, and contrast dyes should be used cautiously or avoided in CKD patients.
10. Smoking: Tobacco use can accelerate kidney damage and should be discontinued.

When to Consult a Nephrologist

Referral to a nephrologist (kidney specialist) is typically recommended in the following situations:

1. eGFR <30 mL/min/1.73 m² (Stage 4 or 5 CKD)
2. Rapid decline in kidney function
3. Persistent proteinuria (protein in urine)
4. Difficult-to-control hypertension
5. Recurrent or extensive nephrolithiasis (kidney stones)
6. Hereditary kidney disease

Early referral has been associated with better outcomes, including reduced mortality rates in the first 90 days of dialysis.

Workup of Kidney Dysfunction

A comprehensive evaluation of kidney function typically includes:

Laboratory Tests:

• Serum creatinine and eGFR calculation
• Urine albumin-to-creatinine ratio (to measure protein loss in urine)
• Complete blood count
• Serum electrolytes
• Lipid profile
• Hemoglobin A1C (for diabetic patients)

Imaging studies

• Renal ultrasonography to evaluate kidney size and structure
• CT or MRI scans in specific cases

Additional Tests (as needed):

• 24-hour urine collection for protein and creatinine clearance
• Kidney biopsy in cases where the etiology is unclear

Conclusion

Chronic Kidney Disease is a complex condition that requires a multifaceted approach to management. By understanding the stages of CKD, the importance of eGFR, and implementing evidence-based strategies, we can significantly improve outcomes for our patients. Early detection, lifestyle modifications, appropriate medication use, and timely referral to nephrology can all contribute to preserving kidney function and enhancing quality of life for those living with CKD.

Remember, each patient is unique, and treatment plans should be tailored to individual needs and circumstances. By staying informed about the latest advancements in CKD management, we can provide the best possible care for our patients.

Sources

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