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.

Amylase in the lung

Although elevated amylase levels in serum, pleural fluid, and extracts of tumor tissue in primary lung cancer have been reported, electrophoretic and column-chromatographic studies have not revealed the ectopic production of amylase but have merely shown an increase of amylase activity of chiefly the salivary type in these materials. The present study was designed to make clear the nature of the amylase or amylase-like substance in the serum, pleural fluid and tumor extracts, and to determine whether amylase might be produced ectopically in tumor tissues. Our data not only confirmed that the hyperamylasemia in some cases of primary lung cancer was due to an increase in salivary type isoamylases, but also showed that the same isoamylase pattern occurs in serum, pleural fluids, and diseased lung tissue of patients with pneumonia. However, the elution pattern of amylase in these materials in column-chromatography on Sephadex G-75 Superfine was different from that of salivary amylase. On the basis of our observations, it seems reasonable to conclude that the salivary type hyperamylasemia in some cases of primary lung cancer may be due to an increase in the amylase contained in normal lung tissues, resulting from activation and release into the blood stream by some inflammatory process. However, ectopic production of amylase was demonstrated in one particular case of primary lung cancer in which a high amylase content and a peculiar isoamylase were found both in the primary and metastatic lesions.

Electrophoretic pattern of amylase isoenzymes in serum and urine of normal persons

We separated and measured amylase isoenzymes in the serum and urine of 3036 normal persons by electrophoresis on a thin layer of polyacrylamide gel. We wished to establish the normal pattern of these isoenzymes and to evaluate the usefulness of this method of electrophoresis in clinical diagnosis. Results for patients with hyper- or hypofunctioning pancreas and salivary glands suggested that essentially all the isoamylases in human serum and urine are derived from the salivary glands and the pancreas, and revealed that isoamylases of more than 98% of normal persons consisted of two major isoenzymes and two to three minor ones. Although these observations indicate that data on changes in the proportion of amylase activity of each isoenzyme can be useful in clinical medicine, the following points should be remembered: (a) quantitative differences in the isoenzyme pattern were observed, depending upon the condition of the samples; (b) because the proportion of isoamylase activity in serum of different normal persons differs, seriatim determination of amylase isoenzymes is necessary; and (c) because five different genetically controlled types of isoamylases were observed in normal persons, genetic investigations are also necessary.