Urine Output Assessment
Enter urine volume, collection interval, and (optionally) patient weight. The calculator reports absolute output and mL/kg/hr for AKI risk stratification.
How to Use This Calculator
Measure urine volume accurately
Collect urine in a graduated container over a defined interval (e.g., hourly output, 6-hour shift, or 24-hour total).
Enter collection duration and weight
Specify collection interval in hours. Include patient weight to evaluate mL/kg/hr threshold for oliguria criteria.
Interpret against KDIGO criteria
Oliguria (≤0.5 mL/kg/hr for ≥6 hours) suggests hemodynamic compromise or evolving AKI and warrants prompt evaluation.
Formula
Urine output (mL/hr) = Volume (mL) ÷ Time (hr)
Urine output (mL/kg/hr) = (Volume ÷ Time) ÷ Weight (kg)
Daily urine output = Volume collected × (24 ÷ hours).
Full Description
Hourly urine output is a cornerstone of kidney perfusion assessment. KDIGO acute kidney injury criteria define oliguria as <0.5 mL/kg/hr for 6 hours and anuria as <0.3 mL/kg/hr for 24 hours. Monitoring urine output guides fluid resuscitation, diuretic use, and escalation of renal support. Pair urine output trends with serum creatinine, hemodynamics, and fluid balance for comprehensive renal assessment.
Frequently Asked Questions
What interval should I use?
ICU protocols often use hourly or 6-hour totals. For general wards, 24-hour collection may be practical. Choose intervals relevant to decision-making.
How does diuretic therapy affect interpretation?
Diuretics can raise urine output despite hypoperfusion. Interpret mL/kg/hr alongside haemodynamics and consider diuretic-induced diuresis.
Does catheter placement change accuracy?
Indwelling catheters provide precise measurements but carry infection risk. Use strict intake/output records if catheters are not indicated.
When should I escalate care?
Persistent oliguria (<0.5 mL/kg/hr for >6 h) or anuria warrants urgent evaluation for AKI and potential nephrology consultation.