Serum Creatinine reference ranges

 Preterm baby:

Day 1      0.9 to 1.8 mg/dL
Day 7      <0.6 mg/dL
1 month    <0.7 mg/dL

 Term baby:
Day 1    1.2 mg/dL
Day 2    the same as above
1 month  the same as above

Reference: Neonatology Review by Dara Brodsky