That's interesting. Why would creatinine in the milk be a problem for the baby. First of all, do we know it gets into the milk? And what if it does at the rate of 10 mg%, say? The baby would be able to handle that. Creatinine, incidentally, is not toxic in itself. It is a marker for renal function. The reason seems farfetched to me. I would encourage this mother to breastfeed and/or provide her milk. The risks to the baby, especially a premature baby, of not getting breastmilk are very high indeed. Jack Newman, MD, FRCPC