1. Pathophysiology

• AKI: Sudden, potentially reversible decline in GFR.
  • Prerenal: Decreased perfusion (hypovolemia, shock, HF). Oliguria occurs without tissue damage; reversible with fluids.
  • Intrarenal: Direct tissue damage, 90% from Acute Tubular Necrosis (ATN) (ischemia, sepsis, nephrotoxins).
  • Postrenal: Mechanical obstruction (BPH, calculi) causing urine reflux.
• CKD: Gradual, irreversible nephron loss (GFR <60 for >3 months). Primary causes: Diabetes (50%), Hypertension (25%). Stage 5 (ESRD) GFR <15.

2. Clinical Phases & Manifestations

• AKI Phases:
  • Oliguric (<400 mL/d): Fluid overload (edema, hypertension, pulmonary edema), acidos ...