The normal urine output is approximately 1mL/kg/h, which puts the average normal urine output around 70mL/h, or 1.7L/day. Theoretically, required urine output depends on the concentrating capacity of the kidney and the amount of free water to be excreted. Oliguria is defined as urine output of less than 0.5mL/kg/h.
Classification of AKI by urine output
- Stage I - <0.5mL/kg/h for 6-12 hours
- Stage II - <0.5mL/kg/h for more than 12 hours
- Stage III - <0.3mL/kg/h for at least 24 hours OR anuria for more than 12 hours
Rule out catheter blockage before testing
Required tests:
- Volume status
- Urine dipstick
- Urine
- Renal function test
Consider:
- Urine microscopy and/or culture
- Blood gas
- Urine osmolality
Treatments
- Crystalloid: 500mL over 10 minutes - see fluid resuscitation