Progesterone radioimmunoassay using 125I-labelled progesterone-TME and comparison with kits by Sorin company

The progesterone level was determined in the normal menstrual cycle using progesterone-6β-TME after Midgley and an antiserum prepared by Midgley and Niswender and the Sorin kit. In agreement with the literature 1 ng/ml was determined for the folicular stage and the progesterone level increased after ovulation to reach maximum on the 6th day after ovulation (12.3+-1.7 S.E.); for a period of 7 days the level exceeded 4 ng/ml. Using the Sorin kit a level of 40.5+-21.6 (S.D.) ng/ml was determined already in the second month, in the eighth it had reached 196.0+-100.9 (S.D.) ng/ml and dropped to 161+-73.1 (S.D.) ng/ml in the tenth month. Using the iodine-labelled preparation all obtained values were higher and without any detectable drop in progesterone level before delivery. The results obtained with the use of the Sorin kit were more reliable. The disadvantage of the kit is its high cost. (L.O.)