Serum immunoreactive trypsinogen (IT) levels were measured in 479 normal controls and in 604 patients (510 with nonpancreatic diseases and 94 with pancreatic diseases) in order to evaluate the distribution of IT values in the control population and the accuracy of the assay in the diagnosis of pancreatic diseases. IT concentrations were normally distributed in the healthy population; children showed mean IT values significantly lower than adults. The sensitivity, specificity, and predictive value of a positive and negative result in diagnosing acute or chronic pancreatitis were evaluated vs normals and vs normals plus all patients. With an IT value higher than 80 ng/ml, the likelihood that a patient is not affected by acute pancreatitis is less than 5%. An IT value lower than 9 ng/ml detected 44% of chronic pancreatitis and was related to a 52% probability of such a condition. The 48% false positive results also include patients with pancreatic tumor (31% of cases), so that the chance of finding reduced IT levels in subjects without pancreatic damage drops to 17%. In view of the low prevalence of pancreatic diseases, IT assay should not be taken into consideration as a diagnostic screening test in the general population and its use should be limited to a hospitalized population.
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