The characteristics of amylase activity and the isoamylase pattern in serum and urine of infants and children.

Determination of amylase activity and isoamylase patterns were performed in serum and urine of normal newborns, infants and children of different ages. In the serum of newborn infants measurable amounts of amylase were present. The activity increased with the age and reached the normal adult level by approximately 8 months of age. Isoamylase analysis revealed that the low level of serum amylase in infants was mainly due to deficiency of the pancreatic-type isoamylase. The absence of the pancreatic isoamylase in newborns and young infants is a physiological and developmental phenomenon. Great caution is therefore necessary when amylase isoenzymes are used in the diagnosis of abnormal pancreatic function and such results have always to be interpreted in relation to the age of the child.