Question

Which among the following is preferred in a patient with decreased renal function to avoid contrast nephropathy?

• A. N-acetylcysteine
• B. Fenoldopam
• C. Low osmolar contrast media
• D. Mannitol

Hint:

The most reliable measure attacks the cause: use a less osmotically toxic contrast agent.

Answer 1

The Correct Option is C

Step 1: Understand contrast-induced nephropathy.
Iodinated contrast can injure the kidney through direct tubular toxicity and renal medullary ischaemia. High-osmolar contrast agents are the most nephrotoxic because the osmotic load worsens medullary hypoxia and tubular damage.

Step 2: Choose the strategy in a patient with poor renal function.
The most reliable contrast-related measure is to use a contrast agent that is itself less toxic. Switching from high-osmolar to low-osmolar (or iso-osmolar) contrast media reduces the osmotic insult and lowers the risk of nephropathy, so this is preferred in patients with impaired renal function.

Step 3: Evaluate the pharmacological agents.
N-acetylcysteine has been used as an antioxidant adjunct, but its benefit is inconsistent and not established. Fenoldopam, a dopamine-1 receptor agonist, has not shown reliable protection. Mannitol, an osmotic diuretic, does not prevent contrast nephropathy and may worsen it. None of these is the preferred measure compared with simply choosing a safer contrast medium.

Step 4: Conclusion.
Correct answer: Low osmolar contrast media.