Which of the following is a prerenal cause of acute renal failure?

UP NHM CHO 7 Sept 2022 (Shift-2)

Medical & Surgical Nursing

Easy

Appeared in: UP NHM CHO 7 Sept 2022 (Shift-2)

Explanation

Prerenal causes of acute kidney injury (AKI) are characterized by reduced blood flow (perfusion) to the kidneys.
Hypovolemia refers to a state of decreased circulating blood volume, which can result from dehydration, hemorrhage, or severe burns.
This reduction in blood volume directly leads to decreased renal perfusion, causing a drop in the glomerular filtration rate (GFR) and resulting in prerenal AKI.
If the underlying hypovolemia is corrected promptly, kidney function can often be restored before permanent damage occurs.

Option A: Nephrotoxic injury involves direct damage to the kidney tissue itself, specifically the tubules. This classifies it as an intrarenal (or intrinsic) cause, not prerenal.
Option B: Prostate cancer causes obstruction of urine outflow from the bladder. Any obstruction in the urinary tract after the kidneys is classified as a postrenal cause of AKI.
Option C: Acute pyelonephritis is a bacterial infection and inflammation of the kidney parenchyma and renal pelvis. Since it involves direct damage and inflammation within the kidney, it is an intrarenal cause.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Classification of Acute Kidney Injury (AKI) causes as background academic context rather than a clinical decision trigger.
Nurses play a critical role in preventing prerenal AKI by closely monitoring a patient's fluid status, including intake and output, daily weights, and assessing for signs of dehydration or volume loss.
Early recognition of hypovolemia (e.g., tachycardia, hypotension, poor skin turgor) and prompt intervention with fluid resuscitation as ordered can prevent the progression from prerenal AKI to more severe intrarenal damage (Acute Tubular Necrosis).
What if? If a patient with heart failure develops AKI, the cause is still prerenal due to decreased cardiac output and renal perfusion, but the treatment would be different. Instead of aggressive fluid administration, treatment would focus on improving heart function with diuretics and inotropes.

How to Approach the Question

First, identify the core concept of the question, which is the classification of causes for 'acute renal failure' (also known as Acute Kidney Injury or AKI).
Recall the three main categories: Prerenal (before the kidney - perfusion issues), Intrarenal (in the kidney - direct damage), and Postrenal (after the kidney - obstruction issues).
Analyze the keyword 'prerenal'. This means you are looking for a condition that decreases blood flow to the kidney.
Evaluate each option against this classification:
Nephrotoxic injury: 'Toxic' implies direct damage to the kidney tissue (Intrarenal).
Prostate cancer: This can cause a blockage of urine flow (Postrenal).

Concept Tested & Keywords

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E6 Medicine Davidson Principles Practice 24e p. 431-433

E6 Medicine Harrison 22e Part 2 p. 284-286