Testosterone free in Saliva ELISA

Background:At present, the majority of steroid hormone determinations are conducted from serum samples, even if results in the low or very low concentration range are expected, for example, in elderly patients. This is a challenge for any diagnostic laboratory as shown by Taieb et al. in 2003 and others. There has been an official position statement of the Endocrine Society stating that reliable testosterone measurements in serum need either an extraction step or have to be done by chromatographic methods like Tandem MS or GCMS. There now is sufficient evidence that the commercial testosterone assays are unable to quantify low concentrations in a reliable way. Another major problem associated with the measurement of free hormone levels from serum is the episodic secretion pattern of steroid hormones. Even in 1973 it could be shown that steroid secretion shows a significant episodic pattern. Nevertheless, the majority of the determinations are still made from just one serum sample, resulting in non-reproducible values due to the biological variation. In general, serum measurements can only give the total steroid hormone concentration, whereas saliva testing results in the measurement of the free active hormone fraction. So far, all attempts for a direct quantification of free testosterone in serum or plasma samples by commercial immunoassays have failed. Taking into consideration the above mentioned drawbacks of the current analytical procedures, salivary testing seems to be a reliable alternative. It has been shown in the literature that the measurement of free salivary testosterone gives clinically valid results even in the low concentration range. In salivary testing it is easy to compensate for the episodic secretion pattern provided multiple sampling is done (preferably five samples within two hours). The measurement of free testosterone is done with a mixture of these five samples. In contrast to this, measurements from just one single saliva sample always will give arbitrary results (like in serum). Measurement of salivary testosterone is used as an adjunct in the diagnosis of disorders involving the male sex hormones (androgens), including primary and secondary hypogonadism, impotence in males and in females hirsutism (excessive hair) and virilization (masculinization) due to polycystic ovaries, and adrenogenital syndromes. Salivary testosterone further permits a good non-invasive characterization of pubertal maturation stages.

Description:
The Testosterone free in Saliva ELISA is a solid phase enzyme-linked immunosorbent assay (ELISA) based on the competition principle. An unknown amount of antigen present in the sample and enzymelabeled antigen compete for the binding sites of antibodies coated onto the wells. After incubation, the unbound conjugate is washed off. The amount of bound peroxidase conjugate is inversely proportional to the concentration of testosterone in the sample. After addition of the substrate solution, the intensity of color developed is inversely proportional to the concentration of testosterone in the sample. The enzymatic reaction is stopped by addition of stop solution and the optical density (OD) is measured. A standard curve is constructed by plotting OD values against concentrations of standards, and concentrations of unknown samples are determined using this standard curve.

Product features:
The kit contains reagents for 96 determinations;
Microtiter plate consisting of 12x8 (breakapart);
Microtiter plate reader at 450 nm;
Analytical sensitivity: 6,1 pg/mL;
IVD.