Cortisol is a steroid hormone released from the adrenal cortex in response to an hormone called ACTH (produced by the pituitary gland), it is involved in the response to stress; it increases blood pressure, blood sugar levels, may cause infertility in women, and suppresses the immune system.  

Cortisol acts through specific intracellular receptors and has effects in numerous physiologic systems, including immune function, glucose-counter regulation, vascular tone, substrate utilization and bone metabolism. Cortisol is excreted primarily in urine in an unbound (free) form.  

Cortisol is bound, in plasma, from corticosteroid-binding globulin (CBG, transcotin), with high affinity, and from albumin. Only free cortisol is available to most receptors.

These normal endogenous functions are the basis for the physiological consequences of chronic stress - prolonged cortisol secretion causes muscle wastage, hyperglycaemia, and suppresses immune / inflammatory responses. The same consequences arise from long- term use of glucocorticoid drugs.

The free cortisol fraction represents the metabolically active cortisol. In normal conditions, less then 1% it comes excrete in urines. In pathological conditions (syndrome of Cushing) the levels of free urinary cortisolo are elevate, because the CBG don?t bound the plasmatic cortisol in excess and it was remove with urines.  

During pregnancy or estro-progestogen treatment an increase of plasmatic cortisol caused by an increment of the production of the transport protein, but the levels of free urinary cortisol results normal to indicate correct surrenic functionality.  This test is very useful to estimate the real surrenic function, because is dose the free cortisol, it is the metabolically active form. Moreover the measurement of free urinary cortisolo is the better parameter for the diagnosis of the Cushing?s syndrome.

May be diagnosed by:

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

Urinary Cortisol ELISA:

The Urinary Cortisol ELISA is intended for competitive immunoenzymatic colorimetric method for quantitative determination of Urinary Cortisol in human urine.

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 50 samples is r = 0.976

Order information: