Effects of plasma sample storage on blood ammonia, bilirubin, and urea nitrogen concentrations: cats and horses.

This research involved studying how the cold storage of plasma samples from cats and horses affects the concentrations of blood ammonia, bilirubin, and urea nitrogen. The study found that the ammonia concentration increased significantly with prolonged storage, especially in horse samples, while the levels of urea nitrogen and bilirubin remained largely stable.

Introduction of Research

• The research was conducted using plasma samples from ten horses, a pony, and 13 cats and aimed to understand the effects of prolonged storage at -20 degrees Celsius on the concentrations of blood ammonia, bilirubin, and urea nitrogen.

Ammonia Concentrations

• Base-line plasma ammonia concentrations in cats did not change significantly after 48 hours of storage, but increased 4.2-fold and 13-fold respectively after 168 and 216 hours of storage.
• Contrary to cats, the base-line plasma-ammonia values in horses were significantly lower and increased from base-line values after 48 hours of storage, continuing to rise over the test period (25.6-fold increase at 168 hours and 18.4-fold at 216 hours).

Bilirubin and Urea Nitrogen Concentrations

• For both cats and horses, the plasma urea nitrogen concentrations did not change significantly during 168 hours of storage.
• Similarly, total plasma bilirubin values for both species did not change significantly during storage.

Main Conclusions

• The findings suggest that plasma samples for ammonia determinations in cats may be safely stored at -20 degrees Celsius for up to 48 hours, after which the concentration starts to increase.
• For horse plasma, ammonia values began to increase during that same time period, suggesting a different storage method may be needed. The reason behind this increase was not determined through the research.
• Plasma samples for both cats and horses in terms of urea nitrogen and total bilirubin showed stability for at least 168 hours of storage at -20 degrees Celsius.