Urine output less than ______ mL/24 hours is known as anuria.

Appeared in: Raj. CHO - 2023

Explanation

Anuria is the medical term for the non-passage of urine, clinically defined as a urine output of less than 100 mL over a 24-hour period.
This minimal urine output signifies that the kidneys are not producing urine, which can be due to severe kidney failure or a complete obstruction of the urinary tract.
It is considered a medical emergency requiring immediate investigation and intervention to prevent complications.

Option A: A urine output of 800 mL in 24 hours falls within the lower end of the normal range for an adult, which is typically 800-2000 mL per day.
Option B: A urine output of 500 mL in 24 hours is not anuria. This level of urine output is classified as oliguria.
Option D: A urine output of 300 mL in 24 hours is characteristic of oliguria, not anuria. Oliguria signifies a low urine output, whereas anuria is the virtual absence of it.

Visual 1: Chart - A comparative chart illustrating the 24-hour urine volumes for anuria, oliguria, normal output, and polyuria, helping to visually differentiate the terms.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Definition and classification of urine output volumes, specifically anuria as background academic context rather than a clinical decision trigger.
Accurate monitoring and documentation of urine output are critical nursing responsibilities, as changes can be the earliest sign of acute kidney injury (AKI) or fluid imbalance.
Anuria is a medical emergency. A nurse's first action is often to check for mechanical obstruction (like a kinked catheter) and then promptly notify the physician.
What if? If a patient's urine output was 350 mL over 24 hours, the correct term would be oliguria, not anuria. This would still warrant investigation for causes like dehydration or early kidney injury, but the urgency and underlying pathology are different from anuria.

How to Approach the Question

Identify the core concept: The question asks for the specific quantitative definition of 'anuria'.
Scan the options: The options are all numerical values in mL, representing different levels of urine output.
Recall medical terminology: Access your knowledge of renal-related definitions. Differentiate between anuria (no/very little urine), oliguria (low urine), and polyuria (excessive urine).
Select the value that matches the definition of anuria, which is the most severe reduction in urine output (less than 100 mL/day).

Concept Tested & Keywords

Concept Tested: Definition and classification of urine output volumes, specifically anuria.
Stem keywords: Urine output, anuria, mL/24 hours
Lead-in keywords: less than

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