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Updated: Dec 1 2021

Renal Papillary Necrosis

  • Snapshot
    • A 60-year-old woman presents to the emergency room with fever, chills, sudden flank pain, and gross hematuria. She has a history of recurrent urinary tract infections. Urinalysis reveals pyuria, hematuria, proteinuria, and dead tissue. An intravenous urography is obtained, revealing a ring sign. She is immediately given hydration and appropriate antibiotics.
  • Introduction
    • Clinical definition
      • necrosis and sloughing of renal papillae
  • Epidemiology
    • Incidence
      • 30-40% in those with sickle cell disease or trait
    • Demographics
      • middle-aged adults
      • uncommon in children, except in those with sickle cell disease or trait
    • Risk factors
      • sickle cell disease or trait
      • acute severe pyelonephritis
      • analgesics such as NSAIDs
        • one of the most common and preventable risk factors
        • phenacetin
      • diabetes mellitus
      • tubulointerstitial nephritis
      • kidney stones causing obstruction
      • indinavir (anti-retroviral drug)
      • congenital urinary tract obstructions such as posterior urethral valves
      • shock
  • Etiology
    • Pathogenesis
      • in sickle cell disease or trait
        • increased blood viscocity in the renal medulla causes renal papillary infarcts
          • the renal medulla has a low oxygen tension resulting in red blood cell sickling
      • in analgesic use
        • NSAIDs inhibits prostaglandin synthesis
          • prostaglandins promote vasodilation
  • Presentation
    • History
      • may be chronic and asymptomatic or acute
      • gross blood in urine
      • may have history of recent infection or autoimmune flare
      • pyelonephritis
    • Symptoms
      • primary symptoms
        • fever and chills
        • sudden onset flank or abdominal pain
      • may be asymptomatic
    • Physical exam
      • tenderness to palpation in the flank or abdomen
  • Imaging
    • Radiographs
      • indications
        • if obstruction such as kidney stones is suspected
        • not diagnostic
      • recommend views
        • kidneys, ureters, and bladder (KUB)
      • findings
        • hydronephrosis from obstruction
        • may visualize kidney stones
    • CT
      • indications
        • typically performed if patient presents with hematuria, even if renal papillary necrosis is suspected, as hematuria can indicate malignancy in the bladder
        • if renal obstruction is suspected
        • most accurate test
      • views
        • CT of abdomen and pelvis
      • findings
        • hydronephrosis
        • kidney stones
        • ring shadows in medullae
        • loss of papillae
    • Intravenous urography
      • indications
        • if CT scan is inconclusive and suspicious for renal papillary necrosis remains high
        • if there is no suspicion of obstruction but suspicion of renal papillary necrosis remains high
      • findings
        • shrinkage of renal papillae
        • ring shadow from desquamated papillae - “ring sign”
        • filling defect in renal pelvis
        • contrast-containing tiny cavities in papillae
  • Studies
    • Labs
      • serum creatinine
        • if there is a sudden rise in creatinine, consider renal papillary necrosis in patient with diabetes or chronic urinary obstruction
    • Urinalysis
      • best initial test and results may show
        • hematuria
        • pyuria
        • proteinuria
        • sloughed papillae
  • Differential
    • Nephrolithiasis
      • kidney stone seen on imaging without evidence of renal papillary necrosis
    • Tubulointerstitial nephritis
      • often presents with rash, arthralgias, and eosinophilia in the urine
  • Treatment
    • Conservative
      • avoid analgesics or any other nephrotoxic medications
    • Medical
      • supportive care with fluid resuscitation
        • indications
          • for all patients
      • antibiotics
        • indications
          • if pyelonephritis is suspected
  • Complications
    • Chronic pyelonephritis
    • Sepsis
  • Prognosis
    • Prognostic variable
      • negative
        • concomitant diabetes
        • older age
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