ELISA for quantitative measurement of 17β-Estradiol in saliva

The 17β-Estradiol Saliva ELISA from Tecan is an enzyme immunoassay developed for performing quantitative measurement of 17beta-Estradiol in human saliva.

  • Regulatory status — EU: CE
  • Kit size — 12 x 8
  • Method — ELISA
  • Incubation time — 2 x 1 hours, 1 x 30 minutes
  • Standard range — 2–64 pg/mL
  • Specimen/volumes — 50 µL saliva
  • Substrate/isotope — TMB 450 nm

17β-Estradiol (Estradiol; E2) is the most vital natural estrogen. It is present in women and men. In women, the estrogens trigger the growth of sex organs and the formation of secondary sexual features, and they also disturb the gonadotropin secretion. 17β-Estradiol measurements are beneficial to spot estrogen deficiency in primary and secondary amenorrhea, delayed puberty and in postmenopausal women typically.

The latest IBL International 17β-Estradiol Saliva ELISA is calibrated to the LC-MS/MS reference technique and comprises harmonized reagents within the IBL Saliva ELISA product series. The 17β-Estradiol Saliva ELISA can be automated without difficulty on open platforms like the EVOlyzer® from Tecan.

Benefits of the 17β-Estradiol Saliva ELISA

  • Just 50 µL sample volume required
  • Calibration to the LC-MS/MS
  • Same sample diluent within the salivary steroid ELISA line
  • Clear reference values: monthly profiles for menstruating women and standard values for postmenopausal women and men

ELISA vs mass spectronomy

Mass spectrometry (MS) is said to be the reference for steroid hormone quantification. However, this method signifies a huge investment and is not present in all laboratories. The key IBL saliva assays have been created to correlate to this reference technique, and even more significantly, they only need low sample volume to measure the steroid hormones.

Excellent correlation of IBL International 17β-Estradiol Saliva ELISA to the LC-MS/MS reference method.

Excellent correlation of IBL International 17β-Estradiol Saliva ELISA to the LC-MS/MS reference method. Image Credit: Tecan

Consistent and reliable processing within saliva product line

Tecan’s Saliva ELISA product line (Cortisol, Progesterone, Testosterone, Estriol, 17β-Estradiol and DHEA) can be processed in a similar manner and be easily carried out in combination:

  • The kits have as few as six standards and two controls
  • The TMB, washing and stop solutions can be interchanged*
  • Just 50 µL (maximum of 100 µL) sample volume is needed
  • All kits employ the same sample diluent buffer

*conditional that the same lot number is used for each component.

Automation

The IBL International 17β-Estradiol Saliva ELISA (Cat. No. 30121045) is versatile and can be used on various ELISA processors. Open automated systems such as the EVOlyzer® from Tecan have been verified and demonstrate a good correlation to the manual operations.

Excellent correlation of IBL International 17β-Estradiol Saliva ELISA on the EVOlyzer®. The combined use of assays, process script and automate has to be validated individually on site by each laboratory.

Excellent correlation of IBL International 17β-Estradiol Saliva ELISA on the EVOlyzer®. The combined use of assays, process script and automate has to be validated individually on site by each laboratory. Image Credit: Tecan

Physiology and time-dependent concentration

Estradiol is discharged into circulation by the ovaries, adrenal gland, placenta and testes or is created by extra-glandular conversion of secreted androgen precursors. Estradiol is biologically the most active of the naturally formed human estrogens. In postmenopausal women, Estradiol arises from the extra-glandular conversion of androgens and flows in low, non-cyclic concentrations.

Salivary Estradiol concentrations in prepubescent children and males are low and non-cyclic. The variations in the hormone levels are recorded during the various phases of the menstrual cycle.

Reference values measured with the IBL 17β-Estradiol saliva ELISA. Saliva samples were collected from 28 women (using no contraceptive). They collected five samples a day during a period of 2 hours after awakening covering the whole menstrual cycle with a maximum of 30 days. Samples were pooled per day and the estradiol concentration was measured to obtain a daily value throughout the menstrual cycle.

Reference values measured with the IBL 17β-Estradiol saliva ELISA. Saliva samples were collected from 28 women (using no contraceptive). They collected five samples a day during a period of 2 hours after awakening covering the whole menstrual cycle with a maximum of 30 days. Samples were pooled per day and the estradiol concentration was measured to obtain a daily value throughout the menstrual cycle. Image Credit: Tecan

Similar to progesterone and testosterone, 17β-Estradiol also displays short-time pulsating dynamics, particularly in women. Thus, single saliva determinations will give rise to arbitrary values. It is recommended to take 3 to 5 samples of saliva within 2 hours.

In the lab, equal measures of the individual saliva samples can be blended. This blended sample leads to a mean 17β-Estradiol value, which signifies the active hormone concentration in a reproducible manner.

Applications of 17β-Estradiol determination

In women, the estrogens trigger the development of sex organs and the formation of secondary sexual features, and they also impact gonadotropin secretion. In men, the role of 17β-Estradiol is less distinct although it appears to be involved in the control of gonadotropin secretion.

In non-pregnant women, 17β-Estradiol is nearly completely created by the ovary. After entering menopause, estrogens are created by the brain, the liver and the muscles as well as by the adipose tissue.

Furthermore, the measurement of 17β-Estradiol is useful to establish a deficiency of estrogens, which may be seen as primary and secondary amenorrhea, delayed puberty and menopause.

Other hormone assays are necessary for correct analysis and differential diagnosis. The concentration of gonadotropin must be quantified to detect the origin of the deficiency of estrogens (synthesis or regulation).

The determination of 17β-Estradiol is beneficial for the diagnosis of pubertas praecox in girls. Regarding men, the level of 17β-Estradiol may be required for the differential diagnosis of gynecomastia.

Measurement of 17β-Estradiol in saliva

Being mainly tied up to sex hormone-binding globulin (SHBG) and serum albumin, just 1-3% of estradiol flowing in plasma exists in its free form. Only this portion signifies the active part in the endocrine regulation. The free hormone is discharged in equal quantities in saliva.

Thus, quantifying the 17β-Estradiol in saliva is a suitable non-invasive technique. Simpler collection of samples without repeated venipunctures and minimized stress on the specimen offer advantages to the patient while accuracy and sensibility of the results are guaranteed.