Causes of acute kidney injury in COVID-19 patients
| Cause | Supporting evidence |
|---|---|
| Prerenal (volume depletion) | Increased blood urea nitrogen: creatinine ratio (> 20), urine sodium < 20 mmol/L, fractional excretion of sodium < 1% Urine sediment may show hyaline casts |
| Acute tubular injury | Urine sodium > 20 mmol/L, fractional excretion of sodium > 1% Urine sediment with granular or muddy brown casts |
| Acute interstitial nephritis | Rash, eosinophilia, white blood cells on urine microscopy Urine sediment with white blood cell casts (urine eosinophils are not sensitive or specific) |
| Postrenal (obstruction) | Bladder scan with high postvoid residual volume, oliguria improving with Foley catheter placement Kidney ultrasonography showing hydronephrosis |
| Rhabdomyolysis | Increased serum creatine kinase and myoglobin in urine Positive urine dipstick for blood, no red blood cells on microscopy |
| Abdominal compartment syndrome | Increased intra-abdominal pressure (> 20 mm Hg) |
| Coagulopathy | Elevated prothrombin time, partial thromboplastin time, D-dimer, fibrinogen |
| Cardiorenal syndrome | Jugular venous distention, low ejection fraction on echocardiography, urine sodium < 20 mmol/L |