Weight to urine output
Reading File
Finding Sources
Searching the Web
urine output mL/kg/hour normal values clinical significance oliguria
Reading File
Reading File
Here is a complete, clinically organized summary of urine output relative to body weight:
Urine Output by Body Weight: Clinical Reference
Normal Values
| Population | Normal Urine Output |
|---|---|
| Adults | 0.5 - 1.0 mL/kg/hour |
| Children | 1.0 mL/kg/hour |
| Infants / Neonates | 1.0 - 2.0 mL/kg/hour |
For a 70 kg adult, this means roughly 35-70 mL/hour (or ~840-1680 mL/day) is the expected range.
Abnormal Urine Output Thresholds
Oliguria (Low Output)
- Adults and children: < 0.5 mL/kg/hour
- Infants: < 1.0 mL/kg/hour
Oliguria is one of the earliest clinical signs of renal hypoperfusion and can precede creatinine rise in acute kidney injury (AKI).
Anuria
- < 100 mL/24 hours (essentially no urine output)
Polyuria (High Output)
- Generally > 3 L/day in adults; may indicate diabetes insipidus, uncontrolled diabetes mellitus, or post-obstructive diuresis.
KDIGO AKI Staging by Urine Output
| AKI Stage | Urine Output Criterion |
|---|---|
| Stage 1 | < 0.5 mL/kg/h for 6-12 hours |
| Stage 2 | < 0.5 mL/kg/h for ≥ 12 hours |
| Stage 3 | < 0.3 mL/kg/h for ≥ 24 hours, OR anuria for ≥ 12 hours |
(KDIGO = Kidney Disease: Improving Global Outcomes)
Clinical Significance
Urine output is one of the most important bedside indicators of:
- Renal perfusion - low output can mean hypovolemia, hypotension, or low cardiac output
- Response to fluid resuscitation - target UO 0.5-1.0 mL/kg/hour during resuscitation
- Renal function - though normal UO does not exclude impending renal failure
As noted in Schwartz's Principles of Surgery: "With a patent Foley catheter, urine output is a gross indicator of renal perfusion... it is important to recognize that normal urine output does not exclude the possibility of impending renal failure."
Using Urine Output to Guide Fluid Resuscitation
According to Bailey and Love's Short Practice of Surgery:
- Target: 0.5-1.0 mL/kg/hour
- If UO drops with signs of hypoperfusion (tachycardia, cool peripheries, high lactate): give a fluid bolus of 10 mL/kg
- If UO exceeds 2 mL/kg/hour: reduce infusion rate (avoid over-resuscitation)
Special Contexts
| Context | Target UO |
|---|---|
| General adult | 0.5-1.0 mL/kg/h |
| Major surgery / ICU monitoring | ≥ 0.5 mL/kg/h |
| Burns resuscitation | 0.5-1.0 mL/kg/h (adults); 1.0 mL/kg/h (children) |
| Rhabdomyolysis | 1-3 mL/kg/h (higher target to flush myoglobin) |
| Post-cardiac surgery | ≥ 0.5 mL/kg/h |
Key takeaway: The fundamental formula is 0.5 mL/kg/hour as the minimum acceptable urine output in adults. Values below this threshold, especially sustained over 6+ hours, warrant immediate assessment for AKI, volume depletion, or obstruction.
This is a shared conversation. Sign in to Orris to start your own chat.