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The choice of any single value for a numerical upper limit of acceptable serum creatinine before concern is raised for the possible induction of contrast-induced nephropathy (CIN) is, to a substantial degree, arbitrary. A physician is always allowed, and should in fact be encouraged, to apply his or her own best judgment based on personal experience, the situation of the individual patient, and current knowledge of risk factors. Indeed, the normal serum creatinine value for younger patients is lower than for adult populations. What is unknown is whether the generally lower renal function in infants and children implies a greater risk of CIN in pediatric populations. In mild disagreement with the letter author(s), it was never stated in the publication that a “creatinine greater than 1.5 mg/dl is a strong indicator of possible contrast-induced renal damage”. CIN is a rather rare consequence of contrast medium administration, regardless of renal function. Nonetheless, serum creatinine is one of the few measurable parameters associated with risk, even if only a poor indicator of what will evolve. Personally, I know of no data showing the risk of CIN to be higher in younger patients despite their reduced excretory capacity. Maybe other risk factors for CIN, such as diabetes, should be weighted more heavily when deciding to avoid contrast medium use for fear of renal damage. As stated in the originally published article, the decision to use a particular drug “should always be a matter of clinical judgment,” but it may not be an easy or sharply defined decision. …