Karen Bailey
In our February newsletter we advised you of a recent update to the interpretation guidelines for canine serum Trypsin-Like Immunoreactivity (TLI) test results. These changes were provisional pending further studies to refine the clinical cut-off limits for diagnosis of canine exocrine pancreatic insufficiency (EPI).
More information has recently become available confirming the original findings, whilst further defining the cut-offs. We will consequently be amending the guidelines as detailed below.
Current interpretive guidelines for canine TLI
· < 2.5 ng/mL diagnostic for EPI.
· 2.6 – 7.5 ng/mL subnormal cTLI concentration, highly suggestive of EPI. Assess response to pancreatic enzyme replacement therapy to confirm diagnosis.
· 7.6 – 10.0 ng/mL subnormal cTLI concentration, EPI cannot be excluded. If signs are consistent with EPI, consider assessing response to pancreatic enzyme replacement therapy to confirm diagnosis.
· 10.1 – 50.0 ng/mL result is within the reference interval.
· > 50 ng/mL The clinical significance of a cTLI concentration >50.0 ng/mL is uncertain. If you have also run a cPLI and this is within the reference interval, pancreatitis is unlikely.
From Monday 17 June 2024 the following amended interpretive guidelines will come into effect on reports. Of particular note is the change to the diagnostic cut-off level indicated in bold.
New guidelines for canine serum TLI interpretation
< 5.5 ng/mL* diagnostic for EPI.
5.6 – 7.5 ng/mL subnormal cTLI concentration, EPI cannot be excluded. If signs are consistent with EPI, consider assessing response to pancreatic enzyme replacement therapy and/or retesting in 1-2 months using a fasting sample (enzyme therapy does not interfere with testing).
7.6 – 10.8 ng/mL subnormal cTLI concentration but EPI unlikely. Consider other differentials depending on clinical signs.
10.9 – 50.0 ng/mL result is within the reference interval.
> 50 ng/mL in dogs without clinical signs of pancreatitis or with a normal cPLI, results > 50 ng/mL are unlikely to be clinically important.
Comments
Elevations sometimes occur in postprandial samples. Food should be withdrawn for at least 12-15 hours before sampling. Concurrent active pancreatitis may also elevate TLI levels.
*Please be aware of this change when comparing current and historical results.
Reference
Texas A&M University Gastrointestinal Laboratory