| Prerenal ARF |
| I. Hypovolemia |
| A. Increased extracellular fluid losses: hemorrhage |
| B. Gastrointestinal fluid loss: vomiting, diarrhea, enterocutaneous fistula |
| C. Renal fluid loss: diuretics, osmotic diuresis, hypoadrenalism, nephrogenic diabetes insipidus |
| D. Extravascular sequestration: burns, pancreatitis, severe hypoalbuminemia (hypoproteinemia) |
| E. Decreased intake: dehydration, altered mental status |
| II. Altered renal hemodynamics resulting in hypoperfusion |
| A. Low cardiac output state: diseases of the myocardium, valves, and pericardium (including tamponade); pulmonary hypertension or massive pulmonary embolism leading to right and left heart failure; impaired venous return (e.g., abdominal compartment syndrome or positive pressure ventilation) |
| B. Systemic vasodilation: sepsis, antihypertensives, afterload reducers, anaphylaxis |
| C. Renal vasoconstriction: hypercalcemia, catecholamines, calcineurin inhibitors, amphotericin B |
| D. Impairment of renal autoregulatory responses: cyclooxygenase inhibitors (e.g., nonsteroidal anti-inflammatory drugs), angiotensin-converting enzyme inhibitors, or angiotensin II receptor blockers |
| E. Hepatorenal syndrome |
| Intrinsic ARF |
| I. Renovascular obstruction (bilateral, or unilateral in the setting of one kidney) |
| A. Renal artery obstruction: atherosclerotic plaque, thrombosis, embolism, dissection aneurysm, large vessel vasculitis |
| B. Renal vein obstruction: thrombosis or compression |
| II. Diseases of the glomeruli or vasculature |
| A. Glomerulonephritis or vasculitis |
| B. Other: thrombotic microangiopathy, malignant hypertension, collagen vascular diseases (systemic lupus erythematosus, scleroderma), disseminated intravascular coagulation, preeclampsia |
| III. Acute tubular necrosis |
| A. Ischemia: causes are the same as for prerenal ARF, but generally the insult is more severe and/or more prolonged |
| B. Infection, with or without sepsis syndrome |
| C. Toxins: |
| 1. Exogenous: radiocontrast, calcineurin inhibitors, antibiotics (e.g., aminoglycosides), chemotherapy (e.g., cisplatin), antifungals (e.g., amphotericin B), ethylene glycol |
| 2. Endogenous: rhabdomyolysis, hemolysis |
| IV. Interstitial nephritis |
| A. Allergic: antibiotics (β-lactams, sulfonamides, quinolones, rifampin), nonsteroidal anti-inflammatory drugs, diuretics, other drugs |
| B. Infection: pyelonephritis (if bilateral) |
| C. Infiltration: lymphoma, leukemia, sarcoidosis |
| D. Inflammatory, nonvascular: Sjögren's syndrome, tubulointerstitial nephritis with uveitis |
| V. Intratubular obstruction |
| A. Endogenous: myeloma proteins, uric acid (tumor lysis syndrome), systemic oxalalosis |
| B. Exogenous: acyclovir, gancyclovir, methotrexate, indinavir |
| Postrenal ARF (Obstruction) |
| I. Ureteric (bilateral, or unilateral in the case of one kidney): calculi, blood clots, sloughed papillae, cancer, external compression (e.g., retroperitoneal fibrosis) |
| II. Bladder neck: neurogenic bladder, prostatic hypertrophy, calculi, blood clots, cancer |
| III. Urethra: stricture or congenital valves |