What is the most important step in preventing contrast-induced nephropathy in high-risk patients?

• A. Avoid hydration before contrast
• B. Diuretics after contrast
• C. Use high-osmolar contrast
• D. Adequate hydration with isotonic saline before and after contrast administration; consider iso-osmolar contrast and minimizing dose

Answer: (D)

Preventing contrast-induced nephropathy hinges on keeping the kidneys well perfused and protecting them from the toxic effects of contrast. The most effective step is ensuring adequate hydration with isotonic saline around the time of contrast exposure. Giving fluids helps maintain intravascular volume, improves renal perfusion, and dilutes the contrast in the tubules, which reduces tubular toxicity and oxygen deprivation in the kidney medulla.

In high-risk patients, this approach is often paired with using iso-osmolar or low-osmolar contrast and minimizing the total contrast dose to further lower risk. It’s also common to withhold or adjust other nephrotoxic factors (like NSAIDs) when possible.

A strategy that hydrates the patient before contrast but omits this essential volume support, or uses diuretics after contrast, would not protect the kidneys and can worsen risk. Using high-osmolar contrast is associated with greater nephrotoxicity, so it is not preferred.