Abstract
Progesterone concentrations in heparinized plasma harvested immediately after blood collection were compared with levels obtained after storage of the corresponding whole blood for 2 h, 4 h, 6 h, 1 day, 2 days and 5 days at room temperature and in a refrigerator. The blood was taken during the luteal phase from 4 dogs, 4 horses, 4 pigs and 8 cows. For 4 cows the storage time was extended to 9 and 20 days. No significant effect of whole blood storage time on plasma progesterone concentrations could be shown for dogs or pigs. For the horse a slight but significant decrease was demonstrated when the blood was kept at room temperature. For the cow, however, a dramatic decrease was observed even when the blood was stored in the refrigerator. Following incubation of cow’s blood at room temperature, progesterone levels were close to zero after 1–2 days. By further extending the storage period, a reappearance of assayable progesterone could be elicited. For all species it was found that the storage of plasma at room temperature for 5–9 days did not change the progesterone concentrations.