Analysis of illicit glucocorticoid levels in camel hair using competitive ELISA – Comparison with LC–MS/MS

Accurate, sensitive, and rapid screening of performance-enhancing drugs, including glucocorticoids, is critical to combat doping in animal racing sports. Samples of urine, saliva, and serum are usually used for random screening of controlled substances; however, they tend to provide only acute usage and doping information. Hair testing has the potential to detect long-term drug use in racing animals. In the present study, commercially available ELISA-kits were used to rapidly screen and analyze various natural and synthetic glucocorticoids in the hair of camels. The four glucocorticoids that were screened using the competitive ELISA were hydrocortisone, dexamethasone, flumethasone, and methylprednisolone. However, comparison of the results obtained using the ELISA method with our previously published LC-MS/MS assay did not show a good correlation. The results obtained with the ELISA analysis of hair samples of 27 different camels showed that this technique consistently yielded significantly higher levels of glucocorticoids compared with the LC-MS/MS assay. This is an interesting finding and suggests that commercially available ELISA tests may overestimate the amount of glucocorticoids present in camel hair, perhaps due to specificity and cross-reactivity issues.