DBC Free Estriol ELISA

For the quantitative determination of Free Estriol (E3) in human serum and saliva by an enzyme immunoassay. For in vitro use only.

PRINCIPLE OF THE TEST
The Free Estriol (also referred to as unconjugated estriol or uE3 in the literature) ELISA is a competitive immunoassay. Competition occurs between Estriol present in calibrators, controls and patient samples and an enzyme-labelled antigen (conjugate) for a limiting number of anti-Estriol antibody binding sites on the microplate wells. After a washing step that removes unbound materials, the enzyme substrate is added, and approximately 15–20 minutes later the enzymatic reaction is terminated by addition of stopping solution. The resulting optical density (OD), measured with a microplate reader, is inversely proportional to the concentration of Estriol in the sample. A calibrator curve is plotted with a provided set of calibrators to calculate directly the concentration of estriol in patient samples and controls.
Serum and salivary assays follow the same procedure except that the volume of the calibrators, controls and samples dispensed into the microplate wells is 10 μL for serum assays and 20 μL for salivary assays.

CLINICAL APPLICATIONS
Since the production of estriol in pregnant women depends on a healthy maternal-placental-fetal system, the estriol concentration is a marker of both placental and fetal normal development and metabolism; hence the determination of serum or saliva estriol concentration is instrumental for the assessment of fetus health in advanced pregnancy (Berkane et al., 2017).
In non-pregnant women and men, estriol levels are low. Notwith-standing, one common application of salivary tests is the monitor-
ing of the estriol levels in women undergoing hormone replacement therapy (Falah et al, 2015).
Due to the significant temporal fluctuations in the concentrations of this hormone, multiple tests are recommended to obtain reliable results (Fleck et al, 2018).

CALCULATIONS
1. Calculate the mean optical density of each calibrator, control
and sample duplicate.
2. Use a 4 -parameter or 5-parameter curve fit with immunoassay
software to generate a calibrator curve.
3. Read the values of the unknowns directly off the calibrator
curve.
4. If a sample reads more than 30 ng/mL dilute it with calibrator
A not more than 10-fold. The result obtained must be multiplied
by the dilution factor.