• Prerenal azotemia:
  • Hypovolemia (e.g., poor intake, vomiting, diarrhea).
• Intrinsic AKI:
  • Exogenous nephrotoxins: chemotherapy, antibiotics, contrast media.
  • Endogenous toxins: hyperuricemia, hypercalcemia, tumor lysis, paraproteins.
  • Other: radiation, HUS/TTP, glomerulonephritis, amyloid, malignant infiltration.
• Postrenal AKI:
  • Ureteric or bladder neck obstruction.

• Prerenal azotemia:
  • Hypovolemia (surgical losses, diuretics), cardiac failure, vasodilators.
• Intrinsic AKI:
  • Ischemic ATN (even in absence of hypotension).
  • Atheroembolic disease after aortic manipulation/intraaortic balloon pump.
  • Preoperative or perioperative administration of contrast medium.
  • Allergic interstitial nephritis induced by perioperative antibiotics.
• Postrenal AKI:
  • Obstructed urinary catheter, exacerbation of voiding dysfunction.

• Prerenal azotemia:
  • Acute fatty liver of pregnancy with fulminant hepatic failure.
• Intrinsic AKI:
  • Preeclampsia or eclampsia.
  • Postpartum HUS/TTP.
  • HELLP syndrome.
  • Ischemia: postpartum hemorrhage, abruptio placentae, amniotic fluid embolus.
  • Direct toxicity of illegal abortifacients.
• Postrenal AKI:
  • Obstruction with pyelonephritis.

• Prerenal azotemia:
  • Intravascular volume depletion (e.g., diuretic therapy).
  • Vasoactive drugs (e.g., calcineurin inhibitors, amphotericin B).
  • Hepatorenal syndrome, venoocclusive disease of liver (BMT).
• Intrinsic AKI:
  • Postoperative ischemic ATN (even in absence of hypotension).
  • Sepsis.
  • Exogenous nephrotoxins: aminoglycosides, amphotericin B, radiocontrast media.
  • HUS/TTP (e.g., cyclosporine or myeloablative radiotherapy related).
  • Allergic tubulointerstitial nephritis.
• Postrenal AKI:
  • Obstructed urinary catheter.

• Prerenal azotemia:
  • Diminished cardiac output complicating pulmonary embolism, severe pulmonary hypertension, or positive-pressure mechanical ventilation.
• Intrinsic AKI:
  • Vasculitis.
    • Goodpasture syndrome, ANCA-associated vasculitis, SLE, eosinophilic granulomatosis with polyangiitis, polyarteritis nodosa, cryoglobulinemia, right-sided endocarditis, lymphomatoid granulomatosis, sarcoidosis, scleroderma.
• Toxins:
  • Ingestion of paraquat or diquat.
• Infections:
  • Legionnaires disease, Mycoplasma infection, tuberculosis, disseminated viral or fungal infection.
  • AKI from any cause with hypervolemia and pulmonary edema.
  • Lung cancer with hypercalcemia, tumor lysis, or glomerulonephritis.

• Prerenal azotemia:
  • Reduced true (GI hemorrhage, GI losses from lactulose, diuretics, large-volume paracentesis) circulatory volume or effective (hypoalbuminemia, splanchnic vasodilation).
  • Hepatorenal syndrome type 1 or 2.
  • Tense ascites with abdominal compartment syndrome.
• Intrinsic AKI:
  • Ischemic (severe hypoperfusion-see earlier) or direct nephrotoxicity and hepatotoxicity of drugs or toxins (e.g., carbon tetrachloride, acetaminophen, tetracyclines, methoxyflurane).
  • Tubulointerstitial nephritis plus hepatitis caused by drugs (e.g., sulfonamides, rifampin, phenytoin, allopurinol, phenindione), infections (leptospirosis, brucellosis, Epstein-Barr virus infection, cytomegalovirus infection), malignant infiltration (leukemia, lymphoma), or sarcoidosis.
  • Glomerulonephritis or vasculitis (e.g., polyarteritis nodosa, ANCA-associated glomerulonephritis, cryoglobulinemia, SLE, postinfectious hepatitis or liver abscess.

• Prerenal azotemia:
  • Intravascular volume depletion (diuretic therapy, hypoalbuminemia).
• Intrinsic AKI:
  • Manifestation of primary glomerular disease.
  • Collapsing glomerulopathy (e.g., HIV, pamidronate).
  • Associated ATN (older hypertensive males).
  • Associated interstitial nephritis (NSAIDs, rifampin, interferon alfa).
• Other: amyloid or light-chain deposition disease, renal vein thrombosis, severe interstitial edema.

AKI, Acute kidney injury; ANCA, antineutrophil cytoplasmic antibody; ATN, acute tubular necrosis; BMT, bone marrow transplantation; GI, gastrointestinal; HELLP, hemolysis, elevated liver enzymes, low platelets; HIV, human immunodeficiency virus; HUS, hemolytic uremic syndrome; NSAID, nonsteroidal antiinflammatory drug; SLE, systemic lupus erythematosus; TTP, thrombotic thrombocytopenic purpura.