Transplant AKI

Transplant AKI

Background

  • Allograft dysfunction
    • Increase in serum Cr > 25 % from baseline in 1-3 months
    • Failure of creatine to decrease post-transplant
    • Proteinuria >1g/day
  • How to think of transplant AKI?  Categorize dysfunction relative to transplant date
    • Don’t forget about: Pre-, intra- and post- renal
  • Dysfunction by time course:
    • < 1-week post-transplant: [usually managed within transplant hospitalization]
      • Often delayed graft function, can require dialysis in week 1 until graft function
      • Vascular thrombosis of graft vessels, ATN (common in deceased donors)
    •  > 1-week post-transplant (HIGH YIELD)
      • Pyelonephritis/complicated UTI: Fever, abdominal pain, graft tenderness
      • Medication changes: hold new medications if possible
        • Common offenders: NSAIDs, ACE, diuretics, azole antifungals
        • Medication non-compliance: Tacro and cyclosporine (rejection)
      • Tacrolimus (FK) or cyclosporine (CsA) level: supra-therapeutic CNI causes arteriolar constriction and decreased GFR
        • FK levels increase with n/v, diarrhea. FK toxicity also causes n/v, diarrhea (chicken vs egg argument)
        • FK or CsA should be dosed at 6 AM and 6 PM. FK levels must be drawn at 5 am (12-hour trough level) to be reliable for dosing adjustments
      • Hypovolemia: fluids
      • Proteinuria: Transplant patients with 1 g/day proteinuria usually get biopsies
        • Pts are commonly admitted for proteinuria found during chronic monitoring

 

Evaluation

  • Check Cr nadir post-transplant
  • Obtain donor characteristics (CMV status, PRA, % HLA antibodies present)
  • Urinalysis, Protein/Cr spot ratio
  • Always schedule Tacro and cyclosporine level lab draws
  • Check prev. labs for donor-specific antibodies (DSAs)
  • BK & CMV PCR: consider only if unclear source of AKI and no recent titers
    • Avoid Ig assays, if evaluating for disease PCRs are test of choice
  • Renal transplant U/S ($$)? Are you answering a question?
    • < 1 week: If acute graft dysfunction, look for thrombosis or urine/ureter leak
    • > 1 week:
      • Cr does not respond to 48 hours of current management
      • Lack of clear, reversible causes
      • Hydronephrosis (can occur after stent removal 4-6 wks after transplant or due to perinephric fluid collection)
      • Arterial stenosis (velocities in renal artery, tardus parvus waveforms)
      • Perinephric abscess with recurrent UTI/pyelonephritis
      • Urinoma (usually first 2-3 weeks), hematoma (after a biopsy)
    • Unique findings:
      • Resistive indices: reflect central renal vascular compliance
      • High indices in transplant patients signify parenchymal problem (rejection, infection, ATN)
  •  Still Stumped?
    • Viral infections: BK, CMV: check PCRs
    • Adenovirus associated with hemorrhagic cystitis, hepatitis, and nephritis in transplant patients. Check PCRs (Nasopharynx, blood, GI pathogen panel) positivity may suggest
    • Post-transplant lymphoproliferative disease (PTLD): lymphoid proliferations in transplants due to immunosuppression
      • Serious and potentially fatal; Majority occur in the presence of EBV
    • Biopsy: if renal u/s unremarkable likely warrant biopsy to guide therapy
      • ATN vs rejection vs Adenovirus vs recurrent disease (FSGS, lupus, etc.)
  • Post Biopsy Care:
    •  
    • Watch for bleeding and HTN
      • Blood can get into collecting system, then the capsule, and into the perinephric space
      • Page Kidney aka Pressure Tamponade: blood in the capsule compresses renal vessels
      • RAAS surge --> rapid, severe HTN (STAT page the renal fellow)