Cortisol is a steroid hormone produced by the adrenal glands in response to ACTH. It regulates the water and salt balance in the kidneys. Cortisol increases the blood sugar level and has an anti-inflammatory effect. Normally, cortisol levels rise and fall during the day, repeating on a 24-hour cycle (diurnal variation). Highest levels are at about 6 to 8 a.m. and lowest levels are at about midnight. Physical and emotional stress can increase serum cortisol, because of normal response to stress involves increased secretion of ACTH by the pituitary gland.

May be diagnosed by:

• Determination of specific antibodies based on the ELISA technique
• Determination of specific antibodies based on the RIA-technique

Cortisol ELISA:

The Cortisol ELISA is intended for competitive immunoenzymatic colorimetric method for quantitative determination of Cortisol in human serum or plasma.

Principle of the Assay:

Microtiter strip wells are precoated with anti-Cortisol antibodies (solid-phase). Cortisol in the sample competes with added horseradish peroxidase labelled Cortisol (enzyme-labelled antigen) for antibody binding. After incubation a bound/free separation is performed by solid-phase washing. The immune complex formed by enzyme-labelled antigen is visualized by adding Tetramethylbenzidine (TMB) substrate which gives a blue reaction product. The intensity of this product is inversely proportional to the amount of Cortisol in the sample. Sulphuric acid is added to stop the reaction. This produces a yellow endpoint colour. Absorption at 450 nm is read using an ELISA microwell plate reader.

Specific performance characteristics: 

Correlation with RIA performed on 25 samples is r = 0.985

Order information: