Professor Kansas State University, College of Veterinary Medicine Manhattan, Kansas, United States
Abstract: Background Copeptin is a 39 aa peptide produced in the pituitary by post-transcriptional processing of pre-pro-arginine vasopressin, which also produces antidiuretic hormone (ADH). Copeptin and ADH are co-secreted in equimolar amounts into circulation, but copeptin measurement is less impacted by pre-analytic factors than ADH assay. Copeptin is a useful surrogate for ADH secretion in numerous human disorders but its role as a biomarker for ADH release has not been investigated in dogs.
Hypothesis/Objectives Validate a commercial ELISA assay for measurement of canine serum copeptin.
Animals Healthy dogs participating in a voluntary blood donor program
Methods Banked serum samples from nine healthy dogs were analyzed using a commercial copeptin ELISA (Copeptin (Human) EIA Extraction Free kit, Phoenix Pharmaceutical Inc). Assays were performed according to manufacturer’s instructions. Standards and canine samples were analyzed in duplicate. Standard curves were plotted using the 4-parameter logistic (4PL) model. Validation parameters determined were intra- and inter-assay coefficient of variation (CV), recovery, parallelism, and dilutional linearity.
Results Serum copeptin was detected in all samples (n=9). Mean serum copeptin concentration was 1.67 ng/mL (range 0.85-4.09 ng/mL). Intra-assay CV was 8.42% and inter-assay CV was 9.6%. The limits and range of detection were 0.1 -10 ng/ml. The assay displayed dilutional linearity and parallelism. Recovery from spiked samples averaged 147%.
Conclusion The assay displayed acceptable parameters for precision, linearity, and recovery. The results provide an expected range for copeptin in healthy dogs, suggesting that this copeptin assay may be a useful research tool for investigating water balance in dogs.
