[Nutritional and acute phase proteins in preterm newborns: reference standards and interrelations]

The serum concentrations of 5 "nutritional" and 5 "acute phase" proteins were prospectively studied in 3 groups of newborns with nephelometric methods. Group A: 22 healthy breast fed term newborns aged 4 days; group B: 28 healthy enterally fed preterm newborns (mean gestational age 33.3 weeks); group C: 49 preterm newborns (mean gestational age 29.5 weeks) on parenteral nutrition (PN). Infants with surgical procedures, sepsis and liver or renal diseases were excluded. The serum concentrations of almost all proteins were similar or only slightly different among the 3 groups and never related to the weight and chronological or post-conceptional age. Only prealbumin, apolipoprotein A and B and C4 levels were significantly different between term and preterm newborns. Enterally fed preterm infants had lower concentrations of alpha 1 acid glycoprotein and higher albumin, transferrin and apolipoprotein A than PN fed infants. Since the observed differences were usually quite small, we suggest that--at least in clinical practice--common serum reference values of these proteins should be adopted for all healthy growing newborns, whether preterm or at term, enterally or parenterally fed. The inter-relationships between different proteins were studied. Four of the five nutritional proteins were highly correlated one with another and the same was observed for the 5 acute phase proteins. Nutritional proteins as a group did not correlate with acute phase proteins, with the only exception of alpha 1 acid glycoprotein and apolipoprotein A. Thus, the 2 groups of proteins seem to be regulated by different metabolic systems.