Description

The Diagnostic Automation,Inc. Cortisol ELISA kit is a competitive immunoenzymatic colorimetric method for quantitative determination of Cortisol concentration in serum and plasma.

Cortisol is a steroid hormone released from the adrenal cortex in response to a 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. The amount of cortisol present in the serum undergoes diurnal variation, with the highest levels present in the early morning, and lower levels in the evening, several hours after the onset of sleep. Highest levels are at about 6-8 a.m. and lowest levels are at about midnight. These normal endogenous functions are the basis for the physiological consequences of chronic stress - prolonged cortisol secretion causes muscle wastage, hyperglycemia, and suppresses immune / inflammatory responses. The same consequences arise from long-term use of glucocorticoid drugs.

Cortisol(antigen) in the sample competes with horseradish peroxidase-Cortisol(enzyme-labeled antigen) for binding onto the limited number of anti-Cortisol(antibody) sites on the microplates (solid phase). After incubation, the bound/free separation is performed by a simple solid-phase washing. The enzyme substrate (H2O2) and the TMB-Substrate (TMB) are added. After an appropriate time has elapsed for maximum colour development, the enzyme reaction is stopped and the absorbencies are determined. Cortisol concentration in the sample is calculated based on a series by a set of standard. The colour intensity is inversely proportional to the Cortisol concentration in the sample.