Lab values will vary based on gestational age and postnatal age. What is normal for a term infant will not be normal for a 24 weeker. I suggest looking at the tables provided in A. A. Fanaroff, R.J.Martin, Neonatal-Perinatal Medicine. This will give you an idea of how lab values can vary based on gestational age and postnatal age in days.
Hope this helps!
Pip