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Acute Kidney Injury of Kidney Transplant

Background

  • Most patients admitted to medicine services with kidney transplants are >3 months post-op. Therefore, we are typically not managing perioperative complications such as delayed graft function, or hyper-acute rejection. Below are the most common causes of acute kidney injury in kidney transplant recipients.

Evaluation

  • Signs and symptoms of UTI?

  • Assess volume status

  • Review meds for recent medication changes

    • Common offenders: NSAIDs, ACE, diuretics, azole antifungals

    • Medication non-adherence

  • Tacrolimus (FK) or cyclosporine (CsA) level

    • FK levels increase with n/v, diarrhea due to alterations in p-glycoprotein expression within inflamed GI tract

    • FK toxicity also causes diarrhea and volume depletion

  • Proteinuria:

    • Transplant patients with 1 g/day proteinuria usually get biopsies

  • Review donor characteristics (CMV status, PRA, % HLA antibodies present, DSAs)

  • BK PCR: consider only if unclear source of AKI and no recent titers

    • Serum PCR is test of choice

  • Renal transplant U/S (costly and not always warranted)

    • \< 1 week post-transplant: If acute graft dysfunction, look for thrombosis, urine/ureter leak

    • > 1 week post-transplant:

      • 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 -- very concerning when velocity >300), 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)

  • Biopsy

    • To differentiate ATN vs rejection vs BK nephropathy 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 causing Page Kidney (aka Pressure Tamponade)

      • Compressed renal vessels-> RAAS surge --> rapid, severe HTN (STAT page the renal fellow)