Administration of NAC for prevention of contrast nephropathy: what's the latest?

The evidence is mixed and weak and the guidelines (AHA/ACCF vs nephrology) are conflicting. Here's what the authors of a recent CCJM mini-review recommend:

Clarify whether contrast is truly needed

When possible, limit the volume of contrast, avoid repeated doses over a short time frame, and use an iso-osmolar or low-osmolar contrast agent

Discontinue nephrotoxic agents

Provide an evidence-based intravenous crystalloid regimen with isotonic sodium bicarbonate or saline

Although it is not strictly evidence-based, use NAC in patients with significant baseline renal dysfunction (glomerular filtration rate < 45 mL/min/1.73 m2), multiple concurrent risk factors such as hypotension, diabetes, preexisting kidney injury, or congestive heart failure that limits the use of intravenous fluids, or who need a high volume of contrast dye

Avoid using intravenous NAC, given its lack of benefit and risk of anaphylactoid reactions.