Comparison of detectability of elevated amylase of serum and urine in pancreatic diseases by two amylase assay methods using starch substrates of different digestive rates to pancreatic amylase.

Detectability of abnormally high serum and urine amylases was investigated on patients with pancreatic diseases using amylase assays with substrates of different digestive rates to pancreatic amylase. Ratios of amylase activities determined by a chromogenic assay using a Remazolbrilliant Blue R starch (RBB assay) to those by Caraway's assay using a Lintner soluble starch (R/C ratio) were calculated on duodenal and salivary amylases obtained from 16 subjects undergoing a pancreozymin-secretin test. The R/C ratio of the duodenal amylase (M +/- SD = 0.56 +/- 0.12) was significantly higher (p less than 0.01 by F test) than that of the salivary amylase (M +/- SD = 0.36 +/- 0.10). Detectability of above-normal values of serum and urine amylases were compared with two assays in 77 pancreatic patients. The value for serum and urine amylases determined by the RBB and Caraway's assays exceeded the upper limit of normal in 37 and 58% by the RBB assay and 24 and 26% by Caraway's assay, respectively. Degrees of abnormality (ratio of the observed to the upper normal value) in serum and urine amylases were also significantly higher (p less than 0.05 for serum and p less than 0.01 upper for urine) by the RBB assay than by Caraway's assay. The RBB assay was more sensitive than Caraway's assay in detecting elevation of pancreatic amylase in serum and urine.