Free Estriol

Estriol (1,3,5(10)-estratriene-3,16ƒÑ,17ƒÒ-triol; E3) is one of the three major naturally-occurring estrogens produced almost exclusively during pregnancy. Maternal Estriol levels, alone and in combination with hCG and AFP, have been recommended to monitor fetal status. During pregnancy, the production of Estriol depends on an intact maternal-placental-fetal unit. Fetal-placental production of Estriol leads to a progressive rise in maternal circulating Estriol levels, reaching a late-gestational peak which is ~2-3 orders of magnitude greater than nonpregnant levels. In the maternal circulation, Estriol undergoes rapid conjugation in the liver followed by urinary excretion with a half-life of ~20 minutes. Therefore, maternal Estriol levels can provide a dynamic estimate of fetal production rates. In terms of estrogenic activity, Estriol is much less potent than Estradiol Because Estriol concentrations are subject to diurnal and episodic variation, it is common practice to refer serum measurements to a baseline, defined for the patient as either the average or the highest of her three most recent Estriol results.

Catalog number SDL7962
Product type ELISA
Quantity 96 Tests (12×8 breakable strip wells)
Standard range 0.4-30 ng/ml
Analytical Sensitivity 0.4 ng/ml
Sample volume 50 µl/well
Species Human

The SDi Free Estriol ELISA Kit is intended for the quantitative measurement of free Estriol in human serum or plasma.

This Free Estriol kit is a solid phases competitive ELISA. The samples, standards, and controls are incubated with Estriol enzyme conjugate on wells coated with anti-Estriol antibody. Free Estriol in the patient’s serum competes with Estriol enzyme conjugate for binding sites. Unbound serum proteins and Estriol enzyme conjugate is washed off by washing with distilled water. Upon the addition of the substrate, the intensity of color is inversely proportional to the concentration of free Estriol in the samples. A standard curve is prepared relating color intensity to the concentration of the free Estriol.

Storage and Stability
Product should be stored at 2-8 °C. Product is stable for 24 months from the date of manufacturing.

For research use only. Not for use in diagnostic procedures.

Miodovnik M, Mimouni F, Hertzberg VS, Siddiqi TA, Tsang RC: Serum unconjugated Estriols in insulin-dependent diabetic pregnancies: normative data and clinical relevance. Am J Perinatol 5:327-
333, 1988.
Buster JE: Gestational changes in steroid hormone biosynthesis, secretion, metabolism, and action. Clin Perinatol 10:527-552, 1983.
Cañez MS, Lee KJ, Olive DL: Progestogens and estrogens. Infertil Reproduct Med Clin North Amer 3:59-78, 1992.
Levitz M, Raju U, Arcuri F, Brind JL, Vogelman JH, Orentreich N, Granata OM, Castagnetta L: Relationship between the concentrations of Estriol sulfate and estrone sulfate in human breast cyst fluid. J Clin Endocrinol Metab 75:726-729, 1992.
Burtis CA,Ashwood ER:Tietz Textbook of Clinical Chemistry.2nd. edition.W.B. Saunders Company,Philadelphia,1994,p.1863