Comparative diagnostic accuracy of four tubeless pancreatic function tests in chronic pancreatitis.

The comparative sensitivity of 4 tubeless pancreatic function tests was evaluated in 125 patients with proved chronic pancreatitis associated with various degrees of pancreatic insufficiency. NBT-PABA, immunoreactive trypsin (IRT), and pancreatic isoamylase (P-iso) were studied in relation to the fecal chymotrypsin test (FCT) and steatorrhea. In advanced insufficiency (steatorrhea or FCT less than 20 micrograms/g) PABA, IRT, and P-iso were pathologically low in only 70-85% of patients. In less severe pancreatic insufficiency (FCT 21-120 micrograms/g) these tests yielded pathological results in 35-53% of patients. Thus the sensitivity of the three tests was comparable and rather low. IRT values (and P-iso) were constantly low or progressively decreasing in 64% of patients (30/47) studied repeatedly over an average of 17 months. The serum enzyme tests seem, therefore, to be valuable for monitoring pancreatic insufficiency, like the FCT. This is particularly important for the differential diagnosis of acute (reversible) and chronic (progressive) pancreatitis.