Collecting equine whole blood in glass tubes does not decrease adrenocorticotropic hormone concentration compared to plastic tubes.

The research article is a study that investigates whether collecting horse blood in glass tubes and storing it impacts the concentration of adrenocorticotropic hormone (ACTH) differently compared to using plastic tubes. The study concludes that no significant difference is observed and both glass and plastic tubes can be used for this purpose.

Research Design

• This investigation was designed as a cohort study, where the whole blood was collected from 9 horses which were aged 12 years or older. The study included 4 horses diagnosed with pituitary pars intermedia dysfunction and 5 healthy controls.
• The blood samples were collected in both glass and plastic tubes that contained a chelating anticoagulant known as EDTA (ethylenediaminetetraacetic acid). These samples were either centrifuged immediately or stored at a temperature of 4 °C for 2, 4, or 6 hours before the centrifugation process.
• The plasma obtained post the centrifugation was transferred into cryovials, from where the immunoreactive ACTH was immediately measured with a chemiluminescent assay, a method known for its sensitivity and specificity in hormonal measurements.

Findings

• Data collected was analyzed using a two-way repeated-measures ANOVA statistical model. This statistical test helps in understanding if there’s any significant interaction between two independent variables (in this case, tube type and storage time) on a dependent variable (ACTH concentration).
• The study concluded that neither the type of tube used for blood collection (glass or plastic) nor the storage time had a significant effect on the plasma’s immunoreactive ACTH concentration.

Conclusions and Implications

• The findings have clinical relevance, establishing that when the whole blood is stored at 4 °C as whole blood on glass for up to 6 hours, equine immunoreactive ACTH concentrations do not significantly differ from collection and storage on plastic.
• Therefore, both glass and plastic EDTA tubes are deemed suitable for collecting samples and same-day analysis of immunoreactive ACTH concentrations. This flexibility implies that the choice of the blood collection tube can be made based on other factors like cost, availability, or ease of use without causing a significant alteration in the test results.