Pancreatic function testing. Methods to identify exocrine insufficiency

The diagnosis of chronic pancreatitis is ideally established by an appropriate clinical history and confirmatory radiologic imaging. However, in cases where imaging results are normal or equivocal, pancreatic function testing is necessary. Direct (intubation) tests are generally accepted as the best methods for study of pancreatic exocrine capacity, but indirect tests, which are well tolerated and generally simple to perform, are gaining interest. Their shortcoming is that they are too insensitive to reliably differentiate patients with early exocrine dysfunction (ie, before malabsorption has occurred) from controls. Sensitivity is not improved by combining two or more studies. However, several modified tests (eg, two-stage paraaminobenzoic acid test, pancreolauryl test) have improved specificity and are able to distinguish pancreatic from other causes of steatorrhea. Their reproducibility in individual cases is of value in sequential studies and in patients with established pancreatic exocrine deficiency to seek evidence of improvement or deterioration in function and to determine patient compliance with replacement therapy.