Abstract
Somogyi 1 has shown that the amylase content in the blood is rather constant for the individual, while the variations from individual to individual are considerable. The study of the amylase content of the urine, however, reveals great irregularity in the same individual at various periods of the day, without any apparent regularity in the variations. The analytical methods used were those described by Somogyi. 1 , 2 , 3 We found it very important to take into consideration the optimum pH (6.8-7.4) and the optimum salt concentration (0.25-0.4% NaCl).
In healthy human beings the concentration of the enzyme in the urine is greater than in the blood, the ratio of urine amylase to blood amylase being usually between 2:1 and 6:1. These fluctuations in ratio occur in the same person, often in the course of a single day. Great as these variations are, we find that on the whole there is a parallelism between the blood and urinary amylase concentrations; i. e., high blood amylase usually goes with a high urinary amylase, and low blood amylase with a low urinary amylase.
In pancreatic injury, as acute pancreatitis, obstruction of pancreatic ducts or trauma of the gland, there is a tremendous increase in both amylases, but without a shift in the relative concentrations. Since the urinary amylase remains high for a period of about 24 hours longer than the blood amylase, it may be preferable to determine the urinary amylase for the diagnosis of acute pancreatitis.
In conditions where the blood amylase is low, as in severe toxemias of pregnancy, pneumonia, liver abscess, many cases of cholecystitis, obstructive jaundice and diabetes, 1 the urinary amylase is proportionately low. Both occasionally may be zero.
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