Urine output is one of the key indicators of kidney function and overall fluid balance in the body. For adults, a generally accepted “normal” or “adequate” urine output is:
- 0.5 to 1 mL/kg/hour for adults.
Here’s a bit more detail:
- Normal urine output: A typical adult urinary output without any health issues and on a regular fluid intake would produce about 1 to 2 liters of urine in 24 hours. This translates to roughly 40 to 80 mL/hour for an average 70 kg adult. However, when considering the kidney’s function in maintaining homeostasis, a urine output of 0.5 mL/kg/hour is often considered the minimum acceptable output to ensure adequate kidney perfusion.
- Oliguria: This is the term used when urine output is < 0.5 mL/kg/hour, indicating reduced kidney function. Oliguria may suggest dehydration, a significant reduction in blood flow to the kidneys (from conditions like shock or heart failure), or acute kidney injury.
- Anuria: This refers to a urine output of < 100 mL in 24 hours. It’s a severe reduction in urine production and may suggest complete kidney shutdown or severe urinary tract obstruction.
- Polyuria: This term is used when the urine output is significantly above normal, usually over 2.5 to 3 liters in 24 hours for adults. It can be seen in conditions like diabetes mellitus, diabetes insipidus, high fluid intake, and certain stages of kidney diseases.