Acute Renal Failure

Acute Renal Failure   1-1) prerenal azotemia with FENa > 1% ABCD(adrenal insufficiency, bicarbonaturia, CRF complicated by salt wasting  diuretics) 2) intrinsic ARF with FENa < 1% (VONG) vascular disease, obstruction, nonoliguric or nephrotoxic, GN   2. eosinophiluria : allergic interstitial nephritis, atheroembolism   3. acyclovir nephrotoxicity => tubular necrosis muddy brown granular & tubular epithelial cell cast   4. nephrotoxic ARF 조영제, nephrotoxic medication endogenous toxin: myoglubin, hemoglobin, uric acid, oxalate, calcium, myeloid protein(light chain)   5. ACE inhibitor 사용시 ARF 유발가능성이 높은 경우 i) bilateral renal a. stenosis ii) unilateral renal a. stenosis in solitary functioning kidney iii) renal hypoperfusion iv) NSAID v) elderly   6. ACE Inhibitor에 의한 신장 합병증 ATN, Interstitial nephritis hemodynamic deterioration membranous nephropathy   7. ARF때 creatinine상승속도 순서대로: CIA Contrast(3-5일) -> Ischemic(1주) -> Aminoglycoside(2주)   8. cyclosphorine에 의한 ARF기전 i) afferent arterioles vasoconstriction: 주기전 ii) ATN : renal blood flow감소로 인한 GFR↓ -> ischemic change iii) interstitial nephritis(rare)   9. renal autoregulatory response장애로 인한 renal hypoperfusion으로 ARF가 발생하는 경우 cycloxygenase inhibitor, ACE inhibitor   10. heavy proteinuria in ARF : CAR-α는 단백이 넘친다. Cycloxygenase inhibitor, Ampicillin, Rifampin, interferon-α   11. ATN때 anuria는 흔치 않다. anuria가 있다면 흔히 complete obstruction을 의미한다. * ATN에서 anuria를 일으키는 상황 i) bilateral urinary tract obstruction ii) bilateral renal a. obstruction iii) severe hypotension iv) acute cortical necrosis v) RPGN   12. ATN에서 maintenance phase때 GFR이 낮게 유지되는 이유? i) epithelial cell injury -> vasoactive mediator release(endothelin) -> intrarenal vasoconstriction, medullary ischemia ii) medullary blood vessel congestion iii) reperfusion injury : reactive oxygen species, leukocyte, renal parenchymal cell에서 mediator분비 iv) tubuloglomerular feedback: epithelial cell injury자체가 persisitent intrarenal vasoconstriction유발   13. ARF with hemolytic anemia HUS, TTP, toxemia, accelerated hypertension(25%), massive transfusion   14. anemia in ARF impaired erythropoiesis, hemolysis, bleeding, hemodilution, RBC survival↓   15. renal biopsy Ix in ARF <Harrison> i) prerenal & postrenal failure가 배제될 때 ii) azotemia의 원인이 불분명할 때 iii) ischemia, nephrotoxic injury가 아닌 치료가능한 질환이 의심될 때 : anti-GBM disease, necrotizing GN, vasculitis, HUS, TTP, allergic interstitial nephritis iv) atypical feature(gradual onset)   <Cecil> i) nephrotic syndrome ii) systemic disease: SLE, Goodpasture, Wegener's DM(atypical course) iii) hematuria > 6Mo iv) transplanted kidney   16. nephrotic syndrome에서의 ARF원인 1) prerenal : volume depletion 2) intrinsic primary GN, interstitial nephritis(NSAID, rifampin, IFN-α) myeloma cast nephropathy or light chain doposition RVT, severe interstitial edema   17. ARF의 recovery phase때 marked diuresis까 일어나는 이유 tubular cell regeneration되면서 GFR회복 => 기전 i) retained salt & water excretion ii) diuretics지속적 사용 iii) glomerular filtration이 epithelial cell function보다 먼저 회복(=요농축능 장애)   18. Rhabdomyolysis의 대사성 원인 hypokalemia, hypophosphatemia, hypo- or hypernatremia DKA, hyperosmolar state   19. Radiocontrast-induced nephropathy의 가장 중요한 병태생리 intrarenal vasoconstriction : endothelin이 중요한 mediator => direct toxicity보다 주로 intrarenal vasoconstiction에 의한다. 이때 endothelin이 중요한 mediator이며 가장 손상받기 쉬운 부분은 proximal convoluted & straight portion이다.   20. ARF에서 dialysis의 절대적응증 i) uremic syndrome: encephalopathy, bleeding, seizure, pericarditis ii) hyperkalemia, severe metabolic acidosis iii) progressive azotemia(BUN>100 mg/dL) iv) pul. edema   21. ARF의 치료 1) renal vasodilation Ca channel blocker, ANP, endothelin antagonist, NO production modifier 2) antiinflammatory aspects anti-adhesion molecules(anti-ICAM-1, anti-integrin) 3) survival factor: GF, cytokine   22. ARF에서의 nutrition protein restriction(0.6 g/kg), carbohydrate(100 g/d)