Faecal elastase 1 levels in premature and full term infants

Background: Determination of faecal elastase 1 (FE 1) is a simple, relatively inexpensive, non-invasive, highly specific and sensitive test. for determining pancreatic function. Secretion of pancreatic enzymes varies during infancy, but there are almost no specific data on the ontogeny of elastase in human babies. Aim: To study FE 1 levels in preterm and term babies, and to determine the possible effect of gestational and postconceptual age on these levels. Methods: Serial stool samples were collected and tested for FE 1 level from 77 premature and full term infants. FE1 levels were determined by a commercially available enzyme linked immunosorbent assay (ELISA) kit. Results: A total of 232 stool samples were collected from 77 neonates. The FE1 level measured in the first stool sample (meconium) was below normal (200 mug/g stool) in all samples regardless of gestational age. Sixty three neonates had at least two samples tested for FE1 level. The mean (SD) level of FE1 in sample 1 was 45.9 (51.1) mug/g stool and was significantly (p < 0.001) lower than in sample 2 (243.0 (164.9) mug/g stool). The lower the gestational age of the newborn, the more time it took for FE1 to reach normal levels. Conclusions: FE 1 levels in meconium are low, and studies in meconium should be avoided if pancreatic sufficiency is to be determined. FE 1 reaches normal levels by day 3 in term newborns and by 2 weeks in infants born before 28 weeks gestation. Normal levels are reached sooner in infants of more advanced gestational age who start enteral feeding earlier.