Background

Cortisol is also known as hydrocortisone when it is used medicinally, usually as a supplement or for its anti-inflammatory properties. Knowing plasma cortisol levels is useful in identifying a serious lack of cortisol usually found in Addison's disease, or a serious over production of cortisol as in Cushing's syndrome. Cortisol analysis is also frequently used to evaluate the stress levels of a subject. This ELISA is designed for detecting cortisol in biological fluids including urine, plasma, and saliva.

Cortisol Assay Principle

This kit is a competitive enzyme-linked immunoassay (ELISA) for determining levels of cortisol in biological samples including urine, saliva, and plasma. Briefly, cortisol in the samples or standards competes with cortisol conjugated to horseradish peroxidase (HRP) for binding to a polyclonal antibody specific for cortisol coated on the microplate. The HRP activity results in brilliant blue color development when the substrate is added, with the intensity of the color development proportional to the amount of cortisol-HRP bound and inversely proportional to the amount of unconjugated cortisol in the samples or standards.

When measuring urine samples, it is recommended to normalize samples to creatinine to account for variations in fluid intake and excretion.  Creatinine is excreated at a constant rate and can be used to normalize the rate of excretion of other analytes.

Creatinine Assay kit (CR01)