Pre-analytical stability of sorbitol dehydrogenase in equine heparinized plasma.

The research article focuses on establishing the pre-analytical stability of equine sorbitol dehydrogenase (SDH), a marker for liver injury in horses, in plasma samples stored at various temperatures over different duration.

Project Overview

The main aim of this research was to determine the stability of the equine sorbitol dehydrogenase (SDH) enzyme, known to indicate liver injuries in horses, before any analysis is done (the pre-analytical stage). The researchers evaluated whether the enzyme activity is preserved under different storage conditions – room temperature, 4 degrees Celsius, and -20 degrees Celsius, over the span of 72 hours.

Methodology

• The study included blood samples from twenty horses that were admitted to a veterinary hospital for varied reasons.
• The blood samples were taken in lithium-heparin tubes and immediately centrifuged. The SDH analysis was done within an hour of the blood collection (T0).
• Subsequently, portions of plasma (the fluid part of the blood) were stored at different temperatures – in regular room temperature, cooled at 4 °C, and frozen at -20 °C.
• The researchers then measured SDH activity at different intervals: after 4 hours (T4), 24 hours (T24), and 72 hours (T72) to identify any significant changes in SDH values compared to the initial results (T0).

Results

• The study found that SDH values significantly varied from the initial measurement (T0) in samples kept at room temperature and those frozen at -20°, but no significant disparity was identified in the samples stored at 4 °C.
• The activity of SDH remained consistent, with a variation within ±20%, in all samples at all temperature conditions after 4 hours. However, after 24 hours, only the samples kept at 4 °C preserved the SDH activity consistency.
• Bland-Altman plots, a method of data representation, indicated narrow limits of agreement after 4 hours for all storage temperatures and after 24 hours for samples stored at 4 °C.
• Lower error ranges were found in samples stored at 4 °C compared to those maintained at room temperature or -20 °C.

Conclusions

The SDH activity in equine blood exhibits sufficient stability for up to 4 hours under any storage temperature. However, for a duration of 24 hours, it only remained stable when stored at 4 °C. These findings on the pre-analytical stability of SDH could enable its wider use in assessing liver conditions in horses.