Definition:
A progressive, irreversible impairment of renal function characterized by:
- Reduced glomerular filtration rate (GFR)
- Progressive retention of nitrogenous waste
- Disturbances in water, electrolyte, acid-base balance
- Complications like uremia, anemia, mineral bone disorders, and cardiovascular disease
Modern classification refers to it as Chronic Kidney Disease (CKD) – affecting structure and/or function of the kidney for ≥3 months.
Etiology:
- Diabetes mellitus (most common cause in developed countries)
- Hypertension
- Chronic glomerulonephritis
- Others: polycystic kidney disease, obstructive uropathy, chronic pyelonephritis, prolonged use of nephrotoxic drugs
Pathogenesis:
- CKD causes gradual nephron loss
- Remaining nephrons undergo compensatory hyperfiltration, increasing glomerular capillary pressure
- This leads to glomerulosclerosis and tubulointerstitial fibrosis
- Over time, this cycle → progressive decline in GFR and uremic symptoms
- Unlike AKI (which may be reversible), CKD is irreversible
- Lack of erythropoietin → normocytic normochromic anemia
- Impaired vitamin D activation → hypocalcemia, secondary hyperparathyroidism
Staging & Classification:
➤ By Creatinine and Creatinine Clearance:
Creatinine clearance becomes unreliable above 200 μmol/L due to tubular secretion falsely elevating results.