Preferential salivary-type hypoamylasemia in obese children.

Serum levels of total amylase, pancreatic type (P-type) isoamylase, and salivary type (S-type) isoamylase were measured in obese children (153 subjects; mean age, 10.1 years old; 86 boys and 67 girls) before and after weight reduction therapy. Serum amylase activities were determined using p-nitrophenylmaltoheptaoside as a substrate, with or without an antibody added to inhibit the S-type isoamylase. Serum levels of total amylase, P-type isoamylase and S-type isoamylase activities were significantly decreased in obese children with an obesity index more than 50%. S-type and P-type isoamylases showed negative correlation with the obesity index, the correlation coefficient being slightly larger in S-type than in P-type isoamylase. Analysis of the serum amylase activities in obese children who underwent weight reduction treatments showed a negative correlation only between the differences in S-type isoamylase activity and the differences in the obesity index. It may be concluded that the S-type isoamylase activity in serum of obese children is decreased and that it can be increased by reducing their body weight.