How is urine output measured accurately in a hospitalized patient, and what is a typical normal hourly output?

• A. Use a rough estimate based on intake
• B. Monitor total output over each hour with a calibrated device
• C. Use calibrated collection device; normal roughly 0.5 mL/kg/hour (30-50 mL/hour)
• D. Do not monitor hourly output

Answer: (C)

Accurate urine output measurement relies on collecting all urine in a calibrated device so every milliliter is measured and time-stamped. In the hospital, urine is collected in a urometer or a graduated collection bag with clear markings, and the volume is recorded hourly to reflect true hourly output. This precise method provides objective information about kidney perfusion and fluid balance, beyond rough estimates or intake-based judgments.

Normal hourly urine output is about 0.5 mL per kilogram of body weight per hour. For most adults, this corresponds to roughly 30–50 mL per hour (for example, a 60 kg person would be around 30 mL/hour, and a 70 kg person around 35 mL/hour). This measurement helps detect oliguria, which can indicate dehydration, poor perfusion, or kidney injury, and guides clinical decisions.