Estriol (1,3,5(10)-estratriene-3,16α,17β-triol; E3) is a female sex steroid hormone largely associated with pregnancy and fetal development. Fetal adrenal DHEA-S is metabolized in the fetal liver to 16α-hydroxy-DHEA-S, which is then converted to estriol in the placenta. (1,2) By the second trimester, about 90% of the estriol produced is derived from this fetal adrenal DHEA-S. (2) Maternal circulating estriol levels rise progressively during pregnancy, reaching a peak in the third trimester. Production of estriol depends on an intact maternal-placental-fetal unit, and maternal salivary estriol levels have been used to monitor fetal status during pregnancy. (2,3,4,5) Estriol is also used as part of the Tri- or Quad-Screen Test for detection of fetal genetic defects. (6,7)
The physiological roles of estriol in non-pregnant women are not well understood and are under investigation. With respect to estrogenic activity, estriol is generally though to be less potent than estradiol or estrone. However, it has been pointed out that, with regard to nongenomic signaling pathways and functional responses in the pituitary, estriol is a strong estrogen. (8)
Changes in levels of estriol and the other estrogens that occur due to menopause, pregnancy, and hormone replacement therapy have also been studied extensively for relationships to cancer susceptibility. (9,10,11,12,13,14) Estriol has also been investigated for its relation to autoimmune diseases such as multiple sclerosis and systemic lupus erythematosus, since pregnant women show significant reductions in symptoms during the last trimester of pregnancy. (15,16,17,18.19) Estriol has also been examined for its role in bone and lipid metabolism, and its function as a protective neurosteroid. (20,21)
In blood the majority of estriol is bound by serum proteins, with about 14-16 % remaining unbound. (4,22) Unbound estriol enters saliva from blood via intracellular mechanisms, and salivary concentrations closely approximate unbound plasma concentrations. (3,23) There is virtually no protein-bound estriol in saliva. (4) Correlation between serum and saliva samples is highly significant. (24)
The effects of freeze thaw on most biological measures, regardless of biospecimen type, can be dramatic. Analytes in oral fluid are not distinct or different in this way. As a general rule, multiple freeze-thaws should be avoided. The most practical way to address this concern is by aliqouting samples after collection. Some analytes are more resistant to freeze thaw than others. We recommend that investigators consult the literature for the analytes of interest. If there is freeze thaw data for a specific biological measure in traditional biospecimens, it is reasonable to assume this would also be true for saliva.
No, but the literature is rather extensive on this subject for several salivary analytes; especially for salivary alpha-amylase and cortisol. We do not track that information internally.
With modern search tools online, we no longer maintain records of this type. We suggest that you use Pubmed or Psychlit to search the literature or you can Ask An Expert and we will be happy to assist you in your search.
If the analyte you are interested in is not noted in our website, please contact Dr. Granger at [email protected] to find out what developments are in the pipeline.
Salimetrics does not release products for sale if the quality control (QC) testing shows any issues. Here are some probable causes:
1) Can timing of adding reagents be off? For instance with a multichannel you can pipette the conjugate and TMB so many times before you refill, but you can pipette the stop twice as fast because it is a smaller volume. If you do this, it shortens the time the bottom rows have with TMB.
2) Can your washer be uneven and sheering off antibody in the bottom corner? Aspirate and check the amount of fluid left. It should be even in all wells and no wells should be completely dry.
3) Are you mixing faster than recommended? Or slower?
4) Are all reagents completely at room temperature? A bottle of assay diluent takes 2 hours to come to RT. You can pour some off into a smaller tube to warm up quicker for the zero and nsb.
5) Are you leaving the plate come to room temperature BEFORE opening the bag? (Otherwise moisture due to humidity may form in the wells and this is particularly a problem in this high humidity weather)
6) Are your multichannel pipettes dispensing the same amount each time reliably? We discard the first and last dispenses as they are not as reliable.
7) Are you incubating with TMB in the dark? (We no longer recommend aluminum foil.)
8) Are you testing one plate at a time? For example, do not put the standards on 5 plates then go back and fill in with samples. This delays the addition of conjugate to the plates.
9) Clean your plate reader filter. Dust from the lab can collect on the filter.
10) Are you adding assay diluent to the zero in sequence after the standards and not the last thing?
11) Never put the multichannel pipette tips into the wells as you can drag down standard from the wells above it causing lower readings in other wells.
12) Thoroughly blot all wells just before adding TMB but do not let the plate dry out.