[Determination of estradiol-17 beta concentration in the saliva of fertile women during the menstrual cycle by an ELISA-type immunoenzymatic, competitive method].

: In accordance with the lipophilic properties that are presented by steroidal molecules and the easy of their diffusion and ultrafiltration across serum to saliva, a competitive immunoenzymatic method based on the solid phase system (ELISA) is here in described, it aims to evaluate 17B oestradiol during menstrual cycle using saliva as the biological fluid. In order to apply this competitive system, the requirements are: as antigen 17B oestradiol immobilized on a solid phase, anti 17B oestradiol sheep serum, (1er. Ab) rabbit-globulin anti sheep serum (2o. Ab). The latter when it's conjugated to an enzyme will reveal and will evaluate the presence of 17B oestradiol-antibody reaction. This ELISA method offers acceptable results within a quality control program, indicating with respect to sensibility, a minimum detection level of 2.5 pg/ml. The specificity, which depends on the antibody used and its interaction with the structurally related steroids was not significative with oestrone (1.32%) and oestradiol, (2.46%). The recovery of 17B E2 was adequate (90-95%). In the standard curve the interassay coefficient of variation ranged between 3.0-4.8%; in the saliva samples, the intra assay and inter assay coefficient of variation were 7.2-9.4 and 4.8-12.1% respectively. With respect to the biological fluid used, we can say that saliva is one of the most accessible fluids in the human body and it can be obtained daily without problem. One additional advantage is that 17B E2 values showed excellent correlation with the menstrual cycle phases. So, because the safety, low cost and simplicity we think this ELISA method appears to be very convenient in order to measure oestradiol in normal and pathological conditions.