Nephrology: contrast-associated acute kidney injury: practice question

A General Medicine question in the style of the NEET PG paper. Answer it first, then read why the right option is right and why each of the others is wrong.

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General Medicine · Nephrology: contrast-associated acute kidney injury

Sample item

A 68-year-old diabetic man with chronic kidney disease (eGFR 35 mL/min/1.73 m2) needs an urgent contrast-enhanced CT scan. Which measure best reduces his risk of contrast-associated kidney injury?

AProphylactic haemodialysis immediately after the scanBIntravenous isotonic saline before and after the scan with the lowest feasible contrast volumeCForced diuresis with furosemide before the scanDOral sodium bicarbonate tablets given only once after the scan

Original practice item, not a recalled exam question. Nothing here is recorded.

The answer and the reasoning

B. Intravenous isotonic saline before and after the scan with the lowest feasible contrast volume

Contrast-associated kidney injury arises from renal vasoconstriction, medullary hypoxia and tubular toxicity, and risk is higher with diabetes, CKD and volume depletion. Volume expansion with isotonic crystalloid, avoidance of other nephrotoxins such as NSAIDs and a minimal dose of low- or iso-osmolar contrast is the proven preventive strategy. Prophylactic dialysis and diuretics do not help and may harm.

Option by option

A. Prophylactic haemodialysis immediately after the scan
Prophylactic dialysis does not protect residual renal function and exposes the patient to procedure risks.
B. Intravenous isotonic saline before and after the scan with the lowest feasible contrast volume (correct)
Correct. Isotonic volume expansion is the most consistently effective prevention strategy.
C. Forced diuresis with furosemide before the scan
Forced diuresis causes volume depletion and increases the risk of injury.
D. Oral sodium bicarbonate tablets given only once after the scan
A single post-scan oral bicarbonate dose has no proven benefit and does not replace intravenous volume expansion.

Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.

Questions about this General Medicine question

What is the answer to this General Medicine question?

The best answer is B, Intravenous isotonic saline before and after the scan with the lowest feasible contrast volume. Contrast-associated kidney injury arises from renal vasoconstriction, medullary hypoxia and tubular toxicity, and risk is higher with diabetes, CKD and volume depletion.

Why is "Prophylactic haemodialysis immediately after the scan" not the answer?

Prophylactic dialysis does not protect residual renal function and exposes the patient to procedure risks.

Why is "Forced diuresis with furosemide before the scan" not the answer?

Forced diuresis causes volume depletion and increases the risk of injury.

Why is "Oral sodium bicarbonate tablets given only once after the scan" not the answer?

A single post-scan oral bicarbonate dose has no proven benefit and does not replace intravenous volume expansion.

What concept does this question test?

It tests Nephrology: contrast-associated acute kidney injury in General Medicine. Volume expansion with isotonic crystalloid, avoidance of other nephrotoxins such as NSAIDs and a minimal dose of low- or iso-osmolar contrast is the proven preventive strategy. Prophylactic dialysis and diuretics do not help and may harm.

How hard is this question?

We tag it as an application question: it asks you to use a fact on a patient or a finding. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

How should I study Nephrology: contrast-associated acute kidney injury?

For each disease know the classic presentation, the best test, and the first-line treatment. Then use the flashcards and the other General Medicine questions on this site to test what stuck.

Is this a real NEET PG question?

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.