Serum trypsinlike immunoreactivity measurement for the diagnosis of subclinical exocrine pancreatic insufficiency

Dogs (n = 158) with serum trypsinlike immunoreactivity (TLI) concentrations less than or equal to 5.0 mu g/L, were studied. The diagnosis of clinical exocrine pancreatic insufficiency (EPI) was made in 114 of 158 dogs based o n TLI concentration < 2.5 mu g/L and clinical signs typical of EPI (eg, pol yphagia, voluminous feces, weight loss). In 44 of 158 dogs, a single TLI me asurement and clinical signs were not diagnostic. In 9 of 44 dogs, TLI was <2.5 mu g/L, indicating EPI, but the gastrointestinal signs were atypical o r the does were asymptomatic. In 35 of 44 dogs, TLI was 2.5-5.0 mu g/L. All 44 dogs were retested for TLI within 1-27 months (mean, 11.9 months). In 2 0 of 44 dogs, the retested TLI was normal (>5.0 mu g/L). In 4 of 44 dogs wi th clinically diagnosed EPI, the retested TLI was <2.5 mu g/L. In the remai ning 20 of 44 dogs, TLI was persistently <5.0 mu g/L (range, 1.0-4.9 mu g/L ; mean, 3.1 mu g/L). Of these dogs, 15 had no clinical signs of gastrointes tinal disease, and 5 had occasional clinical signs atypical for EPI. Gross examination of the pancreas (12 dogs) showed that the amount of normal panc reatic tissue was remarkably diminished. These dogs were diagnosed with sub clinical EPI. The TLI-stimulation test, in which TLI is measured before and after stimulation with secretin and cholecystokinin, showed a significant response (P < .05) both in dogs with subclinical EPI and in control dogs, b ut showed no response in dogs with clinical EPI. In this study, EPI was dia gnosed in its subclinical phase by TLI concentrations persistently < 5.0 mu g/L, and a single TLI concentration < 5.0 mu g/L was not diagnostic. Retes ting after TLI concentrations < 5.0 mu g/L is recommended even in clinicall y normal dogs, because of the possibility of subclinical EPI.