Clinical Guide to Chronic Kidney Disease

Introduction to Chronic Kidney Disease (CKD)

• CKD is a progressive disease resulting in gradual kidney function loss.
• It impacts millions globally, with high rates of morbidity and mortality.
• Healthcare costs associated with CKD are significant.
• Classification is based on glomerular filtration rate (GFR), which measures kidney function.

Epidemiology of CKD

• Approximately 10-15% of the adult population worldwide has CKD.
• Prevalence increases with age; prevalent in individuals with hypertension, diabetes, and cardiovascular diseases.
• Higher incidence observed in certain ethnic groups, notably African Americans, Hispanics, and Native Americans.

Etiology and Risk Factors

• Common Causes:
  • Diabetes Mellitus: Leading cause (30-40% of cases).
  • Hypertension: Second most common (25-30% of cases).
  • Glomerulonephritis: Inflammation of glomeruli.
  • Polycystic Kidney Disease: Genetic disorder causing renal cysts.
  • Obstructive Nephropathy: Resulting from kidney stones, tumors, or prostate enlargement.
  • Chronic Infections: Includes recurrent urinary tract infections and chronic pyelonephritis.
• Risk Factors:
  • Age over 60 years.
  • Family history of CKD.
  • Obesity and smoking.
  • Existing cardiovascular disease.
  • Long-term use of nephrotoxic medications, such as NSAIDs.

Pathophysiology of CKD

• CKD leads to progressive nephron function loss.
• Damaged nephrons trigger compensatory mechanisms in remaining nephrons, causing hyperfiltration and hypertrophy.
• Increased glomerular pressure and proteinuria from compensatory mechanisms result in further nephron injury.
• Over time, fibrosis and scarring occur, contributing to worsening kidney function.

Classification and Staging of CKD

• CKD classification is determined by estimated GFR (eGFR) and presence of albuminuria.
• KDIGO classification is widely recognized:
  • Stage 1: eGFR ≥90 mL/min/1.73 m² with kidney damage.
  • Stage 2: eGFR 60-89 mL/min/1.73 m² with kidney damage.
  • Stage 3a: eGFR 45-59 mL/min/1.73 m².
  • Stage 3b: eGFR 30-44 mL/min/1.73 m².
  • Stage 4: eGFR 15-29 mL/min/1.73 m².
  • Stage 5: eGFR <15 mL/min/1.73 m² (often referred to as end-stage renal disease).