Table 2. Distinguishing features of ATN from AIN.
| Acute Tubular Necrosis | Acute Interstitial Nephritis | |
|---|---|---|
| Onset following injury | Hours to days | Days to weeks |
| Urine volume | Oliguria < 500 mL/d | Polyuria (> 2,000 mL/d) |
| Clinical features | Hemodynamic instability | Rash (25 – 40%), fever (35 – 70%), back pain (25 – 40%), arthralgia (25 – 40%) |
| Histology | Tubular epithelial cell injury | Interstitial cellular infiltrates, edema, tubulitis |
| Eosinophilia | Absent | Present (35 – 60%) |
| Tubular dysfunction† | Rare | Very common |
| FENa # | > 1% | > 1% |
| Urine microscopy | Epithelial cell and broad granular casts | Hematuria (70 – 90%), pyuria (75 – 85%), eosinophiliuria* (variable) |
| Treatment | Hemodynamic resuscitation, withdrawal of nephrotoxic agent, supportive care | Withdrawal of offending agent, supportive care, limited trial of steroids |
| Prognosis | Recovery (65%), CKD (~ 35%) | Recovery (65%), CKD (~ 35%) |
†See Figure 4 for detail; #fractional excretion of sodium; *assumes more than 5% of urinary leukocytes are eosinophils.