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For patients with symptoms of pancreatitis, measurement of amylase in serum reportedly is more sensitive than that of lipase in acute pancreatitis, whereas lipase reportedly is more specific. However, serum lipase activities exceeding the upper reference limit (URL) have been reported for many patients who did not have pancreatitis. I reviewed the serum lipase and amylase concentrations of 493 consecutive inpatients and emergency department patients for whom both tests were ordered. Serum lipase and amylase activities, determined with an Ektachem 700 analyzer, were less than or equal to URL for 390 patients (83%) and greater than URL for 103. Medical records of 101 of these 103 were reviewed; 18 had acute or chronic relapsing pancreatitis. In this latter group, serum lipase values greater than URL had 100% sensitivity and 84% specificity; those of serum amylase greater than URL had 72% sensitivity and 88% specificity. However, the test combination of serum lipase greater than URL and serum amylase less than or equal to URL also occurred in 84% of the patients in which review of the medical records revealed nonpancreatic gastrointestinal or hepatobiliary disorders as the primary problem (n = 55). Therefore, serum lipase activity measured with the Ektachem assay is also often increased in patients with intra-abdominal disorders that appear to be nonpancreatic.

After indirect stimulation of the pancreas by means of a test meal the intestinal activities of trypsin were determined in 452 subjects, lipase in 117, and phospholipase in 57. Trypsin levels were subnormal in 88%, lipase levels in 80%, and phospholipase levels in 81% of patients with chronic pancreatic disease. The outcome of repeated tests (trypsin) was completely consistent in 20 out of 22 patients. Calculations of ratios between the enzymes studied suggested that lipase was the enzyme most susceptible to pancreatic damage. Also in cases of celiac disease and after Polya gastric resection, the decrease of the intestinal lipase concentrations was more marked than that of the other enzymes. In 9% of the cases of chronic pancreatic insufficiency the diagnosis would have been overlooked if either lipase or trypsin had been determined as the sole enzyme. In clinical practice it is recommended to estimate at least two enzymes, because abnormal ratios may be of diagnostic value and because the two different groups of enzymes provide a mutual check on the secretory capacity of pancreatic enzymes. On the whole, the test was found to be reliable, simple, physiological, and inexpensive in terms of resources, and it is highly recommended as a routine test of the pancreatic function.

Gastrointestinal disease other than hepatobiliary and pancreatic disorders was associated with hourly rates of urinary amylase excretion above the limits of normal for control subjects (88 IU/hour compared with 69 IU/hour). In hepatobiliary disease, excretion rates of more than 88 but usually less than 190 IU/hour were sometimes found. Whilst rates of urinary amylase excretion were not helpful in the diagnosis of chronic pancreatitis or carcinoma of the pancreas, levels above 190 IU/hour were found in acute pancreatitis at a time when the serum levels were also diagnostic. After the acute episode the rate of urinary amylase excretion was moderately elevated for up to six days but did not reach diagnostic levels. Persistent elevation of serum amylase and lipase levels and hourly rates of urinary amylase excretion for more than six days suggested that a pseudocyst had developed. In acute pancreatitis the level of serum lipase was more frequently raised and persisted so for longer than either the serum or urinary amylase. Although the hourly rate of urinary amylase excretion is of little value alone, when performed in conjunction with evaluating the serum amylase and lipase it may provide useful additional evidence of pancreatic disease and it could be useful in the diagnosis of relapsing chronic pancreatitis.