News Notes

POC SAA Levels Reliable to Follow Disease Processes

Veterinarians frequently use serum amyloid A (SAA), an acute-phase protein, as a biomarker for inflammation in horses, but they need the information quickly.

Healthy horses have an SAA of about <0.5 to 20 mg/L, which rises dramatically up to 1,000-fold during an inflammatory or infectious process.

The researchers wanted to know whether a pointof-care (POC) diagnostic (Stablelab by Zoetis) could be a valid and quick way to measure SAA. They compared the measurements to 2 immunoassays—TIA- Hum, which was originally designed for human use, but is used in veterinary medicine, and TIA-Vet, which was designed for veterinary use—with the POC device.

They looked at 3 different concentration ranges using 49 equine serum samples. They found a significant difference in the median SAA results (P<0.0001) among all the tests.

“Highest SAA results were obtained with the POC method; lowest SAA results were analyzed with the TIA-Vet assay. Median (minimum to maximum) values obtained were 1,093 mg/L (4-3,000 mg/L), 752 mg/L (0-2,682 mg/L) and 578 mg/L (0.5-2,25 mg/L) for the POC, TIA-Hum2, and TIA-Vet assays, respectively,” the researchers wrote.

A limitation to the study was its length, which required 2 freeze-thaw cycles to obtain separate aliquots. However, the researchers said the sample age did not affect the equine serum SAA stability.

“Although previous studies show that equine serum SAA is stable over 17 days when stored at room temperature and refrigerated at 4° C, our study suggests that equine serum SAA is stable for much longer when stored at -80° C,” they wrote.

For more information:

Kiemle J, Hindenberg S. Bauer N, et al. Comparison of a point-of-care serum amyloid A analyzer frequently used in equine practice with 2 turbidimetric immynoassys used in human and veterinary medicine. Vet Diagn Invest. 2021 Nov 11 doi: 10.1177/10406387211056029 https://pubmed.ncbi.nlm.nih.gov/34763564/vsu.12607