Final answer:
Oliguria is when urine output is less than 600 mL per day and can be caused by conditions like fever or dehydration, while anuria is the absence of urine production, usually less than 10 mL per day, indicating more serious conditions like renal failure.
Step-by-step explanation:
Oliguria and Anuria Defined
Oliguria is a condition characterized by the excretion of less than 600 mL of urine per day. It can be a symptom of various conditions such as fever, shock, vomiting, and diarrhoea. Oliguria can also indicate a decrease in kidney function and is sometimes associated with acute renal failure, which is delineated by less than 400 mL per day in adults.
Typical urine production in a healthy individual ranges between one to two liters per day, with a minimum of about 500 mL needed to eliminate waste from the body. When production falls below this minimum, the condition is termed as oliguria.
Anuria, on the other hand, is a more severe condition where there is a virtual absence of urine output, typically defined as less than 10 mL per day or no excretion at all. This condition can occur due to several serious health issues such as acute renal failure and nephritis. Anuria often requires immediate medical attention, as it can reflect a critical problem with renal function.
Urine Volume and Conditions Affecting It
While polyuria reflects an excessive amount of urine, typically associated with conditions like diabetes mellitus or diabetes insipidus, oliguria and anuria represent states of significantly reduced urine output. Factors like the concentration of urine and the kidney’s ability to concentrate or dilute urine through osmolality testing are important diagnostic tools. They can indicate how well the kidneys are functioning in response to fluid intake.