You expect a patient in the oliguric phase of renal failure to have a 24 hour urine output less than
**Core Concept**
The oliguric phase of renal failure is characterized by a decreased urine output due to inadequate renal perfusion or intrinsic renal damage. This phase is a critical component of acute kidney injury (AKI), where the **glomerular filtration rate (GFR)** is significantly reduced. The oliguric phase is often associated with **azotemia** and **fluid overload**.
**Why the Correct Answer is Right**
In the oliguric phase, the kidneys are unable to produce adequate amounts of urine, leading to a decrease in **24-hour urine output**. A urine output of less than 400 mL per 24 hours is generally considered oliguric. This reduction in urine output is a result of the kidneys' inability to filter waste products effectively, leading to a buildup of **urea** and other toxins in the blood.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because a urine output of less than 400 mL is a more accurate definition of oliguria.
**Option B:** This option is also incorrect as it does not accurately reflect the urine output expected in the oliguric phase.
**Option C:** This option is incorrect because it is higher than the expected urine output in oliguria.
**Clinical Pearl / High-Yield Fact**
It is essential to monitor urine output closely in patients with renal failure, as oliguria can lead to severe complications, including **hyperkalemia** and **pulmonary edema**.
**Correct Answer:** D. 400 mL