Chymotryptic activity in stool of low birth weight infants in the first week of life.

Pancreatic enzyme activity in low birth weight (LBW) infants during the first postnatal week has been evaluated by analysing the chymotrypsin content of 198 stool specimens from 42 LBW infants with birth weights ranging between 750 and 2570 g. A wide variation in chymotryptic activity yet with a tendency to initially low values with a peak on the third day after birth was found. Small-for-gestational age (SGA) infants had significantly lower values than appropriate-for-gestational age (AGA) infants. This is considered due to intra-uterine malnutrition with secondary pancreatic dysfunction in SGA infants. In screening program for cystic fibrosis or other defects of exocrine pancreatic activity, low stool chymotrypsin values cannot be considered pathological until after the fourth day of life.