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

Area of Science:

• Veterinary Endocrinology
• Equine Internal Medicine
• Diagnostic Assay Development

Background:

• Pituitary pars intermedia dysfunction (PPID) diagnosis relies on measuring adrenocorticotropic hormone (ACTH).
• Concerns exist regarding ACTH binding to glass blood collection tubes, potentially affecting measurement accuracy.
• The clinical impact of using glass versus plastic EDTA tubes for equine ACTH sample collection is unclear.

Purpose of the Study:

• To evaluate the effect of glass versus plastic EDTA tubes on equine ACTH concentrations.
• To determine the impact of storage duration (0-6 hours) on ACTH stability in collected blood samples.
• To assess the clinical relevance of tube material for ACTH measurement in horses.

Main Methods:

• A cohort study involving 9 horses (>12 years old) with and without PPID.
• Whole blood was collected in both glass and plastic EDTA tubes.
• Samples were stored at 4°C for 0, 2, 4, or 6 hours before centrifugation and immediate ACTH measurement via chemiluminescent assay.

Main Results:

• No significant difference in plasma ACTH concentrations was observed between glass and plastic EDTA tubes.
• Storage time up to 6 hours at 4°C did not significantly alter ACTH levels.
• Tube type and storage duration did not significantly impact measured ACTH concentrations.

Conclusions:

• Equine whole blood collected in glass EDTA tubes can be stored for up to 6 hours at 4°C without significantly affecting ACTH concentrations compared to plastic tubes.
• Both glass and plastic EDTA tubes are suitable for the collection and same-day analysis of equine ACTH.
• These findings support the use of either tube type for reliable ACTH measurement in diagnosing equine pituitary pars intermedia dysfunction.