The Cardiovascular
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Urine Output and Fluid Balance

Weight-adjusted urine output rate to help identify oliguria.

Urine Output and Fluid Balance
Urine volume collected
mL
Body weight
Collection period
hours
Complete the fields above to see the result.

When to use

  • Tracking whether measured urine output meets the KDIGO threshold for oliguria as part of AKI staging.

Formula

Urine output rate (mL/kg/hr) = urine volume (mL) / [body weight (kg) x collection time (hr)].

Pearls and pitfalls

  • Sustained duration matters: <0.5 mL/kg/hr for >=6 h and <0.3 mL/kg/hr for >=24 h are KDIGO AKI staging criteria, not single-point cutoffs.
  • Interpret alongside creatinine trend, not urine output alone.

References

  1. Khwaja A. Nephron Clin Pract. 2012;120(4):c179-84 (KDIGO AKI guideline summary).