The influence of some sample handling factors on progesterone and testosterone analysis in goats

This study validated the use of commercially available radioimmunoassay kits for measuring the circulating progesterone and testosterone levels of goats. Progesterone and testosterone levels were then assayed in plasma which was collected from 23 does and 8 bucks. Collections from each animal were divided into three sodium fluoride-potassium oxalate (F/OX), one heparin, and one EDTA tubes and also into a tube without anticoagulant. Plasma from an F/OX tube was separated immediately from the blood cells by centrifugation. Serum or plasma was also separated after storage for 24 hours with F/OX, heparin or EDTA anticoagulant at 22°C or with F/OX at 5°C. A significant decline in assayable progesterone occurred in samples stored at 22°C with each anticoagulant used and in the serum sample. Samples stored at 5°C for 24 hours with F/OX anticoagulant contained concentrations of progesterone which did not differ significantly from those in samples where plasma was removed immediately. Assayable testosterone did not change with the anticoagulant used or vary with the storage temperature when F/OX tubes were stored at 5°C and 22°C for 24 hours. Results indicate that sample storage does influence levels of measured progesterone but not testosterone in goats. Progesterone assay is best done on plasma which is immediately separated from blood cells or on samples which are stored at 5°C.