Foregut mucosal defects: an etiology of hyperamylasemia.

To evaluate a preliminary correlation of hyperamylasemia to upper gastrointestinal bleeding, total serum amylase and serum isoamylase profiles were determined in 50 patients with upper gastrointestinal bleeding. Etiologies of the bleeding were determined in 46 patients including gastritis or duodenitis in 25, gastric ulcers in 12, duodenal ulcers in 3, Mallory-Weiss tears in 3, gastric carcinoma in 2, and esophageal varices in 1. Gastritis or duodenitis was seen incidentally in 14 more patients. Hyperamylasemia was seen in 38 patients, most commonly being due to a rise of both nonpancreatic and pancreatic isoamylases (18 patients). In 13 patients it was due to an elevation of nonpancreatic amylase alone, and in 7 patients secondary to elevated pancreatic isoamylase alone. Acute pancreatitis raises only the pancreatic component and cannot explain the hyperamylasemia in most of these patients. Hyperamylasemia did not correlate to etiology of the bleeding; gastritis or duodenitis present in the majority of these patients appears to be the unifying factor. Since both nonpancreatic and pancreatic amylases are present in the duodenum and the stomach with pyloric reflux, reabsorption of intraluminal amylase across damaged mucosa is postulated as a mechanism to explain the observed isoamylase patterns. The possibility of decreased amylase clearance as an explanation is unlikely. An alternative central nervous system mechanism might be invoked. It is concluded that hyperamylasemia is a complex event which the use of isoamylase analysis is beginning to elucidate. The hyperamylasemia seen commonly in patients presenting with upper gastrointestinal bleeding does not imply the presence of acute pancreatitis.

A correlation between clinical pancreatitis and isoenzyme patterns of amylase.

Fifty-seven patients admitted with the clinical diagnosis of acute pancreatitis had isoamylase analysis on their sera to determine the source of their hyperamylasemia. Our objective was to correlate the isoamylase pattern with our clinical observations. Thirty-nine of 57 patients (68%) had pancreatic hyperamylasemia as expected, but 18 of 57 patients (32%) had normal levels of pancreatic amylase. The hyperamylasemia in the latter group was due either to nonpancreatic hyperamylasemia (16 of 57) of macroamylasemia (2 of 57). Consequently, hyperamylasemia associated with abdominal pain, nausea, and vomiting led to the incorrect diagnosis of acute pancreatitis in 32% of the patients. The measurement of isoamylase profiles can be done rapidly and inexpensively. Knowledge that hyperamylasemia is nonpancreatic in origin may have an important influence on treatment, hospitalization, and the extent of laboratory and radiologic investigation.

Clinical application of organ specific isoamylases.

Since hyperamylasemia with or without abdominal pain is a frequently encountered problem, serum isoamylase analysis in 52 patients was done to see if the organ source of the amylase would be helpful in a clinical setting. Four patterns of hyperamylasemia were found: 1) AMY1 (salivary) hyperamylasemia; 2) AMY2 (pancreatic) hyperamylasemia; 3) Both AMY1 and AMY2 amylase elevated; and 4) macroamylasemia. A variety of conditions other than pancreatitis were associated with hyperamylasemia, and some patients who were thought on clinical grounds to have pancreatitis had raised levels of AMY1 (salivary) amylase. This study suggests that hyperamylasemia alone is a poor indicator of pancreatic disease, and that isoamylase analysis will improve the accuracy with which amylase determinations are used.

Aged amylase: a valuable test for detecting and tracking pancreatic pseudocysts.

Amylase-rich fluid that incubates ("ages") within a pancreatic pseudocyst undergoes a change that can be detected by isoenzyme analysis of amylase from the serum. This aging is a result of deamination of the asparagine and glutamine residues on the amylase molecule. Eighteen of 20 patients with surgically proved pseudocysts had greater than 15% aged (deaminated) amylase in their serum. Levels of aged amylase returned to normal following treatment of their pseudocysts. Twenty of 23 patients with acute pancreatitis had levels of aged amylase below 15% (P less than .05). A criterion of 15% aged amylase resulted in 87% specificity, and 91% sensitivity for the diagnosis of pseudocysts. Because this test is noninvasive and easy to perform, it should become the ideal screen for patients at risk of development of pseudocysts, Endoscopic retrograde pancreatography, ultrasonography, and abdominal computed tomographic scanning should be reserved for confirmation of the diagnosis when the result of isoenzyme analysis is positive.