Pre-analytical stability of adrenocorticotrophic hormone from healthy horses in whole blood, plasma and frozen plasma samples.
Authors: Prutton James S W, Kass Philip H, Watson Johanna L, Pusterla Nicola
Journal: Veterinary journal (London, England : 1997)
Summary
# Editorial Summary: ACTH Stability in Equine Blood Samples Understanding the pre-analytical handling requirements for equine ACTH testing is crucial for diagnostic reliability, yet the hormone's stability characteristics in various sample types and storage conditions had not been systematically documented. Prutton and colleagues collected blood from nine healthy horses and measured ACTH concentrations across multiple storage scenarios: whole blood and plasma held at 4°C or 21°C for up to 72 hours, and frozen plasma maintained at -20°C or -80°C for 30 days. Results demonstrated that ACTH concentrations declined significantly within the first 24 hours regardless of storage temperature, but plasma frozen at either -20°C or -80°C remained stable throughout the 30-day period, with no appreciable loss of ACTH. Practically, this means samples can safely reach the laboratory without centrifugation within 8 hours if kept at ambient conditions, or can be frozen immediately for longer-term storage at standard freezer temperatures without compromising test validity. For practitioners and veterinary clinics, these findings streamline sample handling protocols: prioritise immediate freezing for maximum stability, or maintain unfrozen samples at cool temperatures for same-day submission, whilst avoiding delays beyond 24 hours in non-frozen storage.
Read the full abstract on PubMed
Practical Takeaways
- •If sending ACTH samples to a laboratory, refrigerate at 4°C and submit within 8 hours, or freeze at -20°C or -80°C for storage up to 30 days to ensure accurate results
- •Room temperature (21°C) storage significantly degrades ACTH and should be avoided; this is critical for diagnostic accuracy in equine endocrine disease assessment
- •Samples do not need to be centrifuged immediately if kept cool—allowing more flexibility in field sampling situations
Key Findings
- •ACTH concentration was significantly reduced at 24 hours in whole blood and plasma stored at 4°C or 21°C
- •Plasma frozen at -20°C or -80°C remained stable for 30 days without appreciable reduction in ACTH concentrations
- •Samples stored at 21°C showed greater ACTH reduction beyond 24 hours compared to those stored at 4°C
- •Samples can be stored for 8 hours without centrifugation without appreciable loss of ACTH