The effect of anticoagulant, storage time and temperature, and sodium azide on blood progesterone concentrations

BLOOD PROGESTERONE concentrations in zebu cows were measured at ILCA's research station in Debre Birhan, Ethiopia. Progesterone concentrations in unseparated plasma and serum samples declined rapidly, particularly at high storage temperatures (35°C). The commonly used anticoagulants––lithium heparin, sodium citrate and ethylene diaminetetracetate––did not significantly affect the measured concentrations. Once coagulation had taken place, progesterone concentrations were higher in unseparated serum than in unseparated plasma. Assayable progesterone reappeared in unseparated plasma samples kept for 3 to 7 days. When sodium azide was added to plasma with anticoagulant, 90% of the initial progesterone concentration was preserved over a period of 3–7 days.