[Determination of cortisol, T4, T3 and T-uptake in serum and plasma of horses using fluorescence polarization immunoassays (FIPAs)].

The study investigates the effect of storage conditions – specifically, duration and temperature – on the hormone levels in horse blood, serum, and plasma. Using fluorescence polarization immunoassays, the researchers tested for cortisol, T4, T3 and T-uptake, but were unable to successfully measure T3.

Study Methodology

• The study involved analyzing levels of cortisol, T4, T3 and T-uptake in whole blood, serum and plasma of horses. These measurements were made using a method known as Fluorescence Polarization Immunoassays (FPIAs).
• The T3-FPIA was, however, unsuccessful in measuring T3, implying that this might not be an appropriate method for this hormone.
• Samples stored under the same conditions were compared to identify any significant differences in their hormone values.

Findings on Storage Conditions and Hormone Levels

• The researchers noticed fluctuations in cortisol and T4 levels in frozen heparinized plasma samples that were analyzed on separate occasions. In contrast, the T4 uptake values remained largely stable.
• When the samples were stored at 20-22 degrees C, the day-to-day changes in cortisol and T4 levels in plasma were at their minimum. However, when stored at 4 degrees C, cortisol levels exhibited a notable decrease, but no clear trend was identifiable for T4.

Impact of Temperature on Whole Blood

• A similar trend in hormones changing in response to temperature was observed in whole blood samples.
• Whole blood cortisol concentration reduced more drastically when stored at 4 degrees C than when stored at 20-22 degrees C.
• When stored at 20-22 degrees C, T4 remained stable in whole blood samples over a span of four days. But, there were noticeable fluctuations when the samples were stored at 4 degrees C.

Implications of the Study

• The observed impact of storage conditions on hormone levels has significant implications for future research. The storage temperature and period can potentially impact the accuracy of measurements, therefore, they should be carefully chosen to maintain the stability of the elements being studied.