Accuracy of the plasma amino acid-consumption test in detecting pancreaticdiseases is due to different methods

The aim of this study was to evaluate the controversial specificity of the plasma amino acid (AA)-consumption test in detecting pancreatic diseases by using two different quantitative methods. A total of 55 subjects: 13 healt hy subjects, 13 patients with chronic pancreatitis (three mild/moderate, ei ght severe), 13 patients with pancreatectomy and complete suppression of th e exocrine pancreatic secretion, eight patients with chronic liver disease (five with impaired synthetic function), and eight patients with chronic re nal failure. Total plasma AAs were quantified by a colorimetric method (p-b enzoquinone) in all subjects, at 0, 30, 45, and 60 min during and 30 min af ter minute 60 of i.v. cerulein infusion (50 ng/kg/h). Either total and indi vidual AAs were quantified by chromatography (high-performance liquid chrom atography; HPLC) in 10 healthy subjects, 10 patients with pancreatectomy, a nd 10 with chronic pancreatitis at 0 and 60 min after the start of the ceru lein infusion. For the colorimetric method, healthy subjects had maximal pe rcentage decreases of total AA concentrations not significantly different f rom those of patients with pancreatectomy and significantly higher than tho se of patients with chronic pancreatitis (p < 0.0001) or chronic liver dise ase (p < 0.001). Pancreatic function, as assessed by fecal elastase-l test, was not significantly correlated to the maximal percentage decrease in tot al plasma AAs. For the chromatographic method, total AA concentrations were not significantly correlated to those determined by colorimetry. The conce ntration of each of the individual plasma AAs varied considerably in each g roup. Fecal elastase-1 values were normal (greater than or equal to 200 mu g/g) in all patients without pancreatic disease and in only one of 11 patie nts with chronic pancreatitis and exocrine insufficiency. The type of metho d used can explain the different results of the AA-consumption test. This t est is not very specific for the pancreas.