Urine Output of 800ml in 5 Hours: Assessment and Interpretation
Your urine output of 800ml in 5 hours (160ml/hour or approximately 2ml/kg/hour for a 70kg adult) is actually normal to high-normal and does NOT indicate impaired renal function or dehydration. This output is well above the minimum threshold for adequate kidney function and suggests you are adequately hydrated.
Normal Urine Output Parameters
For healthy adults with normal renal function, the minimum urine output should be at least 0.8-1 L per day (approximately 33-42ml/hour), and your output significantly exceeds this threshold. 1
- Under normal circumstances of diet, exercise, and climate, the minimal urine output for healthy subjects is about 500ml/day (approximately 21ml/hour) 2
- The obligatory urine volume is determined by maximal renal concentrating ability and the solute load which must be excreted 2
- Your output of 160ml/hour is approximately 4-7 times higher than the minimum required output
What This Output Indicates
Your urine output suggests adequate to generous hydration status, not dehydration. 1, 2
- Intake of more than 500ml of fluids per day will result in the excretion of solute-free water, which is what you're experiencing 2
- Higher urine output typically reflects adequate fluid intake and normal kidney concentrating ability
- In healthy individuals, fluid balance is strictly regulated via osmoregulation by vasopressin and the kidneys, combined with the thirst mechanism 2
When to Be Concerned About Renal Function
Oliguria (reduced urine output) is defined as urine output ≤0.5 mL/kg/h or ≤45 mL/h for at least 2 hours despite adequate fluid resuscitation, which would be concerning for renal dysfunction. 1
- For a 70kg adult, this threshold would be approximately 35ml/hour
- Your output of 160ml/hour is more than 4 times this threshold
- Acute oliguria in the context of illness, dehydration, or medication use would warrant investigation 1, 3
Clinical Context Matters
If you are experiencing symptoms such as excessive thirst, dry mucous membranes, or taking medications that affect kidney function (such as RAAS inhibitors, diuretics, or NSAIDs), further evaluation may be warranted despite normal urine output. 3
- Dehydration combined with certain medications can lead to acute renal failure even with initially preserved urine output 3
- Serum osmolality >300 mOsm/kg indicates dehydration in older adults, regardless of urine output 1
- Serum creatinine should be checked if there are concerns about renal function 4
Hydration Adequacy
A wide range of fluid intakes are compatible with normal hydration (euhydration), whereby total body water varies narrowly from day to day by 600-900ml (<1% body mass). 5
- The recommended total daily fluid intake is approximately 3,000ml for men and 2,200ml for women 2
- Your urine output suggests you are likely meeting or exceeding these recommendations
- Higher fluid intake does not have convincing health benefits except perhaps in preventing kidney stones 2
In summary, your urine output is normal and reassuring. No intervention is needed unless you have other symptoms or risk factors suggesting underlying kidney disease or medication-related complications.