Free Estriol Saliva ELISA Kit


Human free estriol saliva ELISA kit is an accurate in vitro quantitative method for detecting free estriol (unconjugated estriol, E3, oestriol) in human saliva samples. This assay has a minimum sensitivity detection limit of 1.4 pg/ml.


Estriol (also known as oestriol and E3) is significantly produced in large amounts during pregnancy due to the fetus. It is regarded as of the one of the three main estrogens that are made by the human body, where its production is dependent on an intact maternal-placental-fetal unit. Due to this fact, the measurement of maternal estriol concentration has been particularly useful in monitoring the fetal status during pregnancy especially in the third trimester. DHEA-S is produced by the adrenal cortex of the fetus and this can be converted to estriol by the placenta. Fetal placental is responsible for producing estriol which results in a progressive increase in the maternal circulating levels that can reach a late gestational peak of many orders of magnitude greater than in non-pregnant levels. If estriol concentrations are abnormally low in a pregnant woman, this can be an indication of a problem with the development of the child.

The following human salivary estriol ELISA kit is intended to measure free estriol to provide acceptable results that are comparable to those using serum samples. It offers the advantage of being a non-invasive process which does not put the patient under any unnecessary stress. Many different bodily fluids can be routinely detected for estriol (E3) in order to monitor and manage the fetal well-being. There are also many advantages for measuring free estriol instead of total serum or urinary E3. Unconjugated/free estriol is found to reflect more accurately the fetal outcome in diabetic pregnancies, since the levels are not affected by certain antibiotics administration or certain maternal hepatic and renal related diseases. Also, the fact that frequent measurement of unconjugated estriol is highly recommended since the ranges for normal and abnormal levels are relatively wide and overlapping.


All reagents supplied need to be stored at 2 °C – 8 °C, unopened reagents will retain reactivity until expiration date. Do not use reagents beyond this date.

  • Microtiterplate (96 wells): Coated with anti-estriol antibody.
  • Calibrators 0-5: Concentration 0, 2.5, 15, 100, 600, 4000 pg/ml, made up from human estriol.
  • Control 1 (Low) And Control 2 (High).
  • Enzyme Conjugate (100x): Consists of estriol conjugated to horseradish peroxidase (HRP).
  • Enzyme Conjugate Dilution Buffer.
  • Substrate Solution: Tetramethylbenzidine (TMB).
  • Stop Solution.
  • Wash Solution (10x Concentrated).


The minimum sensitivity detection limit of free estriol (unconjugated estriol, E3, oestriol) using current human salivary estriol ELISA kit was approximately 1.4 pg/ml. The dynamic range for this assay is 2.5 – 4,000.0 pg/ml.


– Free Salivary Estriol (Free Estriol Saliva): ELISA
– Analytical Sensitivity: 1.4 pg/ml
– Specificity (Cross Reactivity): Highly specific for estriol.
– Assay Dynamic Range: 0 – 4000 pg/ml.
– Intra-Assay Variation: 8.2 – 9.4%
– Inter-Assay Variation: 4.8 – 8.6%
– Recovery: 80 – 109%
– Interfering Substances: Blood contamination in saliva samples was found to affect the results, in this case blood is usually visible with the eye.


  1. Enzyme immunoassay of unconjugated estriol in serum and saliva during pregnancy. Exp Clin Endocrinol. (1985) 86 (2): 178-84. Weissbach A., et al.
  2. ELISA for salivary and plasma estriol in pregnancy. Steroids. (1984) 43 (5): 469-79. Preti M.S., et al.
  3. The measurement of hormones in saliva: possibilities and pitfalls. J Steroid Biochem. (1987) 27 (1-3): 81-94. Review. Vining R.F. and McGinley R.A.
  4. Salivary unconjugated estriol levels in normal third trimester pregnancy – direct correlation with serum levels. Steroids. (1983) 41 (2): 145-53. Kundu N., et al.


  • Full Name: Free Estriol Saliva ELISA Kit
  • Reactivity: Human
  • Sample Type: Saliva
  • Sensitivity: 1.4 pg/ml



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