Oliguria vs. Anuria — What's the Difference?

Oliguria is characterized by a decreased output of urine, typically defined as less than 400 milliliters per day in adults. This condition can indicate various health issues, ranging from dehydration to kidney dysfunction. Anuria, on the other hand, refers to a more severe condition where urine output is extremely low or absent, generally less than 50 milliliters per day. It often suggests significant kidney failure or severe obstruction in the urinary tract.

In oliguria, the kidneys are still producing some urine, but the amount is insufficient. It can be a symptom of conditions like acute kidney injury or chronic kidney disease. In contrast, anuria represents a state where the kidneys have almost completely stopped producing urine. This can be due to complete kidney failure, severe blockages, or catastrophic damage to the urinary system.

The causes of oliguria can vary from simple dehydration to more complex issues such as heart failure or sepsis. It often serves as an early warning sign of kidney trouble. Anuria, however, is usually indicative of more serious health problems and requires immediate medical attention, as it can be caused by severe kidney damage or complete blockage of urine flow.

Treatment for oliguria may involve addressing the underlying cause, such as rehydration for dehydration or medication adjustment for drug-induced low urine output. Anuria, due to its severity, often requires more intensive treatment, potentially including dialysis to perform the kidneys' filtering function.