Factitiously Low Amylase Values

When a commercial substrate was used in the determination of serum amylase activities of patients with acute pancreatitis, results much higher than those re-ported by the manufacturer with similar patients were found. A failure to quantitate all of the reducing groups liberated during incubation may account for the lower results. A modified saccharogenic method has been developed, which, by increasing the ratios of starch to enzyme and copper to reducing sugars, considerably extends the range of the determination. Unequivocally elevated serum and urine amylase values can be measured without repetition of all or part of the test and with good precision. lECENT STUDIES of saccharogenic amylase methods (1, 2) stress the importance of using sufficient substrate to maintain maximum reac-tion velocity during incubation. This paper presents evidence that commonly used spectrophotometric copper reduction methods for the determination of reducing groups in postincubation mixtures have been misapplied, leading to factitiously low amylase values. A modi-fied saccharogenic method, which permits analysis of most pathologic human sera or urines without repetition of either incubation or copper reduction steps and without sacrifice of precision in the normal range, is described. Materials Methyl and propyl p-hydroxybenzoates were obtained from East-man Organic Chemicals Department, tris (hydroxymethyl) amino