March 2024 TLI test results update !!!

[Olesia711]

Texas A&M Gastro Lab has firmed up the TLI test results numbers and interpretation:
https://vetmed.tamu.edu/gilab/service/assays/tli/


INTERPRETATION
Canine trypsin-like immunoreactivity assay

IMPORTANT (updated 3/14/2024): new reference interval and decision thresholds

The cTLI assay we use is a commercial assay made by Siemens that is widely used by veterinary diagnostic laboratories world-wide. We recently became aware that there are dogs with a serum cTLI concentration that is higher than the cut-off value of ≤2.5 µg/L that appear to have exocrine pancreatic insufficiency (EPI). We gathered serum samples from more than 100 healthy dogs to determine if there had been an assay shift, which does appear to be the case. Thus, we have adjusted our reference interval to > 10.9 to µg/L. Importantly, we needed to determine a cut-off value for the diagnosis of EPI in dogs. With help from many of our valued veterinarian clients, we recently completed an observational study to determine a new cut-off value for the shifted assay. We now consider values ≤ 5.5 µg/L to be diagnostic for EPI. Our recommendation for dogs with equivocal cTLI concentrations (5.6 to 10.8 µg/L) AND clinical signs consistent with EPI is to initiate a trial with pancreatic enzyme replacement therapy and to closely monitor the patient’s response. Please note that some dogs with small intestinal disease, but without EPI, can partially respond to pancreatic enzyme replacement therapy. Further, repeating a measurement of serum cTLI 1 to 2 months after initial blood sampling is helpful to determine whether serum cTLI has further decreased and the dog has EPI. All samples should be collected after withholding food for 12 to 18 hours.

Also, some healthy dogs have serum cTLI concentrations >50 µg/L, but cTLI concentrations may also be increased in dogs with pancreatitis or renal insufficiency. Therefore, the clinical significance of a cTLI concentration >50.0 µg/L is uncertain. If you are concerned about pancreatitis, consider running a serum cPLI test as this test is more reliable for diagnosing this condition. In dogs without clinical signs of pancreatitis or with a serum cPLI concentration within the reference interval, a cTLI >50 µg/L is unlikely to be clinically important.

We will keep working to further refine these decision thresholds and as always, we are available to consult on challenging cases.

cTLI interpretations (updated 3/14/2024):

0 to 5.5 µg/L Diagnostic for EPI

5.6 to 10.8 µg/L Subnormal cTLI concentration, EPI cannot be excluded. If signs are consistent with EPI, consider assessing response to pancreatic enzyme replacement therapy and/or remeasuring cTLI in 1 to 2 months using a fasted sample (enzyme therapy will not interfere with testing).

10.9 to 50.0 µg/L Result is within the reference interval.

>50.0 µg/L In dogs without clinical signs of pancreatitis or with normal cPLI concentrations, a cTLI >50 µg/L is unlikely to be clinically important.