333.3 🏥 內科專科考前版

333.3.1 Mechanistic Deep Dive

333.3.1.1 ATN Pathophysiology

  • Tubular epithelial cell apoptosis + necrosis
  • Cytoskeletal disruption
  • Loss of brush border + polarity
  • Cast formation
  • Tubular obstruction + back-leak

333.3.1.2 Ischemic vs Toxic ATN

  • Ischemic: outer medullary stripe (S3 segment)
  • Toxic: more diffuse
  • Histologic distinction difficult

333.3.1.3 AKI Biomarkers

  • NGAL: tubular damage early marker; elevated within hours
  • KIM-1: proximal tubular damage
  • TIMP-2 × IGFBP7 (Nephrocheck): G1 cell cycle arrest markers; FDA approved
  • L-FABP: tubular damage
  • Cystatin C: functional, less muscle-dependent

333.3.1.4 HRS Pathophysiology

  • Splanchnic vasodilation (NO, VIP)
  • Reduced effective circulating volume
  • Renal vasoconstriction (RAAS, sympathetic)
  • Functional AKI without intrinsic damage

333.3.2 Recent Trials & Updates

333.3.2.1 Terlipressin for HRS (CONFIRM 2021)

  • US Phase 3 trial
  • FDA approval 2022
  • More effective than placebo
  • Risk of pulmonary edema (volume + vasoconstriction)

333.3.2.2 Sepsis-AKI Optimization

  • ANDROMEDA-SHOCK
  • Hemodynamic targeting
  • Lactate-guided

333.3.2.3 CA-AKI Updates

  • AMACING trial: hydration vs no hydration similar for low-risk
  • KDIGO 2022 guidelines: contrast safer than thought

333.3.2.4 KDIGO 2024 (Future)

  • Refined definitions
  • Biomarker integration
  • Phenotyping

333.3.2.5 Empagliflozin in AKI Recovery

  • Emerging
  • May reduce CKD progression post-AKI

333.3.3 High-Yield Specialist Points

333.3.3.1 Drug-Induced AKI Mechanisms

Pre-Renal: - ACE/ARB: reduce efferent arteriole tone - NSAIDs: reduce afferent arteriole vasodilation - Diuretics: volume depletion

ATN: - Aminoglycosides: tubular cell accumulation - Vancomycin: oxidative + ischemic - Contrast: ischemia + direct toxicity - Cisplatin: tubular accumulation - Tenofovir: mitochondrial toxicity

AIN: - T-cell mediated hypersensitivity - Penicillins, NSAIDs, PPIs, ICIs - T1/T2 helper response

Crystal: - Acyclovir: crystals in tubules - Methotrexate: crystals - Sulfa: crystals

333.3.3.2 ICI-Associated AIN

  • Pembrolizumab, nivolumab, ipilimumab, etc.
  • T-cell driven nephritis
  • Often AIN pattern
  • Treatment: hold ICI + corticosteroids
  • Can re-challenge after recovery in some

333.3.3.3 Atheroembolic AKI (Cholesterol Embolism)

  • Post-arterial procedure (cath, AAA repair)
  • Subacute (weeks)
  • Livedo reticularis, blue toes, eosinophilia
  • Treatment: supportive; statins; no specific
  • Poor prognosis

333.3.3.4 Hypertonic Hyponatremia + AKI

  • Mannitol, glucose
  • Pseudohyponatremia (HLD, paraproteinemia)

333.3.3.5 TMA-AKI Differential

  • TTP, HUS (typical/atypical), DIC, scleroderma renal crisis, malignant HTN, HELLP, drug-induced TMA
  • Workup: peripheral smear, ADAMTS13, complement, etc.

333.3.3.6 Cardiorenal Syndrome

  • Diuretic resistance common
  • Acetazolamide (ADVOR), tolvaptan (TACTICS-HF)
  • Ultrafiltration (UNLOAD, CARRESS-HF mixed)
  • Heart-kidney transplant

333.3.3.7 Post-Renal Bilateral Obstruction Workflow

  • US first
  • CT urogram if mass / stone
  • Decompression: foley, ureteric stent, nephrostomy
  • Watch post-obstructive diuresis (electrolytes)

333.3.3.8 Recurrent AKI + CKD Progression

  • AKI accelerates CKD progression
  • Survivors at risk
  • Surveillance post-AKI

333.3.4 Pearls

  • KDIGO: Cr ↑ 0.3 in 48 h OR 1.5× in 7 d OR UO < 0.5 mL/kg/h × 6 h
  • Pre-renal: FENa < 1%, BUN/Cr > 20, U Osm > 500
  • ATN: muddy brown casts, FENa > 2%, U Osm isothenuric
  • AIN: WBC casts, ICI / NSAID / PPI / penicillin
  • Post-renal: US for hydronephrosis
  • HRS: terlipressin + albumin (FDA 2022); liver transplant cure
  • Rhabdomyolysis: CK > 5000, aggressive IVF
  • TLS: rasburicase prophylaxis + hydration
  • Biomarkers: NGAL, KIM-1, Nephrocheck (TIMP-2 × IGFBP7)