What is the difference between Chronic Kidney Disease (CKD) and renal failure?

Differences Between Chronic Kidney Disease and Renal Failure

Chronic kidney disease (CKD) is a broader term encompassing abnormalities in kidney structure or function persisting for more than 3 months, while renal failure specifically refers to advanced kidney dysfunction (GFR <15 mL/min/1.73m²) requiring kidney replacement therapy. 1

Definition and Classification

Chronic Kidney Disease (CKD)

• Defined as abnormalities in kidney structure or function present for >3 months with health implications 1
• Diagnosed by:
  • Markers of kidney damage (e.g., persistent proteinuria, abnormal urine sediment, abnormal imaging findings) 1
  • OR decreased GFR (<60 mL/min/1.73m²) for ≥3 months 1
• Classified according to:
  • Cause
  • GFR category (G1-G5)
  • Albuminuria category (A1-A3) 1

Renal Failure (Kidney Failure)

• Defined as either:
  • GFR <15 mL/min/1.73m² (CKD stage G5), accompanied by signs and symptoms of uremia
  • OR need for kidney replacement therapy (dialysis or transplantation) 1
• Represents the most severe stage of CKD 2
• Not synonymous with End-Stage Renal Disease (ESRD), which is an administrative term indicating treatment with dialysis or transplantation 1

Staging and Progression

CKD Stages (based on GFR)

1. Stage G1: GFR ≥90 mL/min/1.73m² with evidence of kidney damage
2. Stage G2: GFR 60-89 mL/min/1.73m² with evidence of kidney damage
3. Stage G3a: GFR 45-59 mL/min/1.73m²
4. Stage G3b: GFR 30-44 mL/min/1.73m²
5. Stage G4: GFR 15-29 mL/min/1.73m² (Advanced CKD)
6. Stage G5: GFR <15 mL/min/1.73m² (Kidney Failure) 1, 3

Advanced CKD specifically includes stages 4 and 5 (GFR <30 mL/min/1.73m²) 3

Clinical Implications

CKD (Earlier Stages)

• Often asymptomatic, especially in early stages 1
• Detected through routine screening (estimated GFR, albuminuria, urine sediment) 3
• Complications begin to increase when GFR falls below 60 mL/min/1.73m² 1
• Focus on:
  • Slowing progression
  • Managing risk factors
  • Treating comorbidities 1

Renal Failure (CKD Stage G5)

• Characterized by:
  • Signs and symptoms of uremia
  • Need for kidney replacement therapy 1
• Significantly higher morbidity and mortality 2
• Focus on:
  • Preparation for and management of kidney replacement therapy
  • Management of complications 1

Complications and Management Differences

CKD Management (Earlier Stages)

• Treatment of comorbid conditions
• Interventions to slow progression
• Measures to reduce cardiovascular risk 1
• Evaluation and treatment of complications begins at stage 3 (GFR <60 mL/min/1.73m²) 1

Renal Failure Management

• Preparation for kidney replacement therapy (dialysis or transplantation)
• Management of uremic symptoms
• More intensive management of complications 1

Cardiovascular Risk

• Cardiovascular disease is the major cause of morbidity and mortality in both CKD and renal failure 4
• Risk increases progressively with declining kidney function 2
• In advanced stages, non-traditional risk factors become increasingly important:
  • Sodium retention and volume expansion
  • Anemia
  • Inflammation
  • Malnutrition
  • Sympathetic overactivity
  • Mineral bone disorders
  • Accumulation of uremic toxins 2

Clinical Pitfalls to Avoid

1. Terminology confusion: Kidney failure is not synonymous with ESRD. ESRD is an administrative term indicating treatment with dialysis or transplantation, not a specific level of kidney function 1

2. Age considerations: Although GFR declines with age, decreased GFR in the elderly is still an independent predictor of adverse outcomes and requires the same attention as in younger patients 1

3. Early detection importance: All patients with CKD stages 4-5 should be referred to nephrology for specialized care 3

4. Overdiagnosis concerns: Early stage CKD in older patients may represent normal aging rather than disease requiring intervention 5

5. Transition planning: Preparation for kidney replacement therapy should begin during stage 4, well before kidney failure develops 1

By understanding these distinctions, clinicians can better identify, monitor, and manage patients across the spectrum of kidney disease, potentially improving outcomes and quality of life.