Diametra Androstenedione Elisa Kit

CLINICAL SIGNIFICANCE
Androstenedione (also known as Δ4-androstenedione) is a steroid hormone produced in the adrenal glands and the gonads as an intermediate step in the biochemical pathway that produces the androgen testosterone and the estrogens estrone and estradiol. It is the common precursor of male and female sex hormones. Some androstenedione is also secreted into the plasma and may be converted in peripheral tissues to testosterone and estrogens.
Androstenedione has relatively weak androgenic activity, estimated at ~ 20% of testosterone. However, serum androstenedione levels often exceed testosterone in both normal and disease states. Secretion and production rates also exceed those of testosterone in women in whom significant extra-adrenal conversion of androstenedione to testosterone occurs.
In premenopausal women the adrenal glands and ovaries each produce about half of the total androstenedione (about 3 mg/day). After menopause androstenedione production is about halved, primarily due to the reduction of steroid secreted by the ovary. Nevertheless, androstenedione is the principal steroid produced by the postmenopausal ovary.
Measurement of serum androstenedione provides a useful marker of androgen biosynthesis. Elevated androstenedione levels have been demonstrated in virilising congenital adrenal hyperplasia. Serum androstenedione levels are also increased in polycystic ovary syndrome, and in case of hirsutism in women. Elevated serum androstenedione levels may also occur in adrenal and ovarian virilising tumours.

PRINCIPLE OF THE METHOD
The Androstenedione ELISA is a competitive enzyme immunometric assay (ELISA) where androstenedione (antigen) in the sample competes with the antigenic androstenedione conjugated with horseradish peroxidase (HRP) for binding to the limited number of antibodies antiandrostenedione coated on the microplate (solid phase).
After the incubation, the bound/free separation is performed by a simple solid phase washing. Then, the enzyme HRP in the bound fraction reacts with the Substrate (H2O2) and the TMB Substrate and develops a blue colour that changes into yellow when the Stop Solution (H2SO4) is added. The colour intensity is inversely proportional to the androstenedione concentration in the sample.
Androstenedione concentration in the sample is calculated through a calibration curve.

QUALITY CONTROL
Good Laboratory Practice (GLP) requires the use of quality control specimens in each series of assays in order to check the performance of the assay. Controls should be treated as unknown samples, and the results analysed with appropriate statistical methods.
The kit control provided in the kit should be tested as unknown and is intended to assist in assessing the validity of results obtained with each assay plate.
The mean concentration of each control level is documented in the QC report included with each kit. These mean concentration levels are determined over several assays which are run in duplicate in multiple locations across each plate.

CALCULATION OF RESULTS
A variety of data reduction software packages are available, which may be employed to generate the mean calibration curve and to calculate the mean concentrations of unknown samples and controls. A 4-parameter logistic (4PL) curve fit, including Calibrator 0 is required. Other curve fitting algorithms are not recommended. Alternatively, a calibration curve may be prepared on semilog graph paper by plotting mean absorbance on the Y-axis against concentration of analyte on the X-axis. Calibrator 0 should be included in the calibration curve.
Read the mean absorbance value of each unknown sample off the curve. In order for the assay results to be considered valid the kit calibrators and control must fall within the specifications detailed in the lot specific certificate of analysis.
If a control is out of its specified range, the associated test results are invalid and samples must be retested.
Conversion of units
To convert results to SI units: nmol/L = ng/mL x 3.49
To convert results to mass units: ng/mL = nmol/L x 0.29