Tests of Exocrine Pancreatic Function

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Abstract
For cases of acute pancreatitis seen shortly after the onset of symptoms, determination of serum or urinary amylase and/or serum lipase suffices in the more severe cases. Moderate increases in these enzymes are not diagnostic. Plain x-ray films of the abdomen may help in differential diagnosis. Serum Ca and ascitic fluid amylase determinations can be misleading at this stage. Repetition of tests and continuous clinical appraisal is indicated, and if doubt as to the diagnosis persists, laparotomy may be needed. In the cases where the diagnosis is established, examination of the serum for methemalbumin gives an indication of the severity of the condition. In patients seen a few days after onset of symptoms, urinary amylase or possibly serum ribonuclease determinations may be helpful. Repetition of serum amylase and lipase determinations is needed if pseudocyst formation is suspected. Recovery of function is best assessed by intubation studies. Investigations for causative factors should be done at the same time. Relapsing pancreatitis is best followed during exacerbations by serum amylase and lipase determinations. Intubation studies are useful later to distinguish relapsing acute pancreatitis from relapsing chronic pancreatitis. Assessment for associated abnormalities such as hypercalcemia, hyperlipidemia or gallstones should be done following recovery. Chronic pancreatitis is difficult to diagnose in the early stages. Duodenal intubation studies using secretin and CCK-PZ [cholecystokinin-pancreozymin] in combination with the evocative test are helpful. Scanning and radiological methods are less satisfactory for establishing the diagnosis but may indicate the presence of a pancreatic carcinoma as the cause of the patient''s symptoms. In the later stages intubation studies are markedly abnormal. A glucose tolerance test may be of the diabetic type, and fecal fat excretion is often high. A reduction in urinary pancreatic amylase may help to avoid the intubation in young children, and fecal chymotrypsin excretion is helpful in assessing and following the degree of dysfunction. Scanning methods and radiological techniques at this stage are able to detect the formation of stones, calcification or cysts. Pancreatic carcinoma frequently causes diagnostic confusion with chronic pancreatitis in the early stages. The same procedures are therefore applicable to both conditions, and cytological examination should be undertaken. A glucose tolerance test is desirable, as it may be abnormal early. Involvement of the bile duct should be assessed by the usual liver function tests and radiological methods. Where doubt exists an exploratory laparotomy is advisable.