Cortisol EIA Kit

Cortisol (C₂₁H₃₀O₅), also known as hydrocortisone, is the primary glucocorticoid hormone produced by the adrenal cortex in response to stress. Often referred to as the “stress hormone, ” cortisol plays a central role in regulating blood pressure, glucose metabolism, immune responses, and circadian rhythms. Its secretion follows an ACTH-dependent diurnal pattern, peaking in the early morning and declining throughout the day. In neuroscience, cortisol is a key modulator of brain function. Chronic dysregulation of cortisol levels has been linked to cognitive decline, mood disorders, and neurodegenerative diseases such as Alzheimer’s and Parkinson’s. Elevated cortisol can impair hippocampal function, reduce neurogenesis, and contribute to neuronal atrophy. Only free cortisol, which constitutes about 4% of circulating levels, is biologically active and capable of binding to glucocorticoid receptors in the brain. Abnormal cortisol levels are associated with psychiatric and neurological conditions including depression, schizophrenia, and Cushing’s syndrome.

The Cortisol EIA kit is designed to quantitatively measure cortisol present in dried fecal extracts, saliva, urine, serum, plasma and tissue culture media samples. This kit measures total cortisol in extracted samples and in serum and plasma and free cortisol in saliva and urine. A cortisol standard is provided to generate a standard curve for the assay and all samples should be read off the standard curve. Standards or diluted samples are pipetted into a clear microtiter plate coated with an antibody to capture mouse antibodies. A cortisol-peroxidase conjugate is added to the standards and samples in the wells. The binding reaction is initiated by the addition of a monoclonal antibody to cortisol to each well. After an 1 hour incubation the plate is washed and substrate is added. The substrate reacts with the bound cortisol-peroxidase conjugate. After a short incubation, the reaction is stopped and the intensity of the generated color is detected in a microtiter plate reader capable of measuring 450 nm wavelength. The concentration of the cortisol in the sample is calculated, after making suitable correction for the dilution of the sample, using software available with most plate readers.

The Cortisol EIA kit is designed to quantitatively measure cortisol present in dried fecal extracts, saliva, urine, serum, plasma and tissue culture media samples. This kit measures total cortisol in extracted samples and in serum and plasma and free cortisol in saliva and urine. A cortisol standard is provided to generate a standard curve for the assay and all samples should be read off the standard curve. Standards or diluted samples are pipetted into a clear microtiter plate coated with an antibody to capture mouse antibodies. A cortisol-peroxidase conjugate is added to the standards and samples in the wells. The binding reaction is initiated by the addition of a monoclonal antibody to cortisol to each well. After an 1 hour incubation the plate is washed and substrate is added. The substrate reacts with the bound cortisol-peroxidase conjugate. After a short incubation, the reaction is stopped and the intensity of the generated color is detected in a microtiter plate reader capable of measuring 450 nm wavelength. The concentration of the cortisol in the sample is calculated, after making suitable correction for the dilution of the sample, using software available with most plate readers.

Intra Assay Precision: Three human samples were diluted with Assay Buffer and run in replicates of 20 in an assay. The mean and precision of the calculated Cortisol concentrations were: Sample 1- 1174.3 pg/mL, 6% CV Sample 2- 475.9 pg/mL, 5.6% CV Sample 3- 177.4 pg/mL, 14.7% CV Inter Assay Precision: Three human samples were diluted with Assay Buffer and run in duplicates in ten assays run over multiple days by four operators. The mean and precision of the calculated Cortisol concentrations were: Sample 1- 1188.1 pg/mL, 7.2% CV Sample 2- 508.7 pg/mL, 6.3% CV Sample 3- 199.7 pg/mL, 10.9% CV

1. E. Friess, et al., Eur J Clin Invest, 2000, 30, Suppl 3:46-50. 2. Freeman, Scott, 2002. Biological Science. Prentice Hall; 2nd Pkg edition (December 30, 2004). 3. C. Longscope., J. Endocrinology, 1996, , Suppl S125-S127. 4. J. Herbert, Lancet, 1995 345, 1193-1194. 5. A. Michael, et al., Biol. Psychiatry, 2000, 48, 989-95. 6. C.R. Dequet and D.J. Wallace, Current Opin. Ivest. Drugs, 2001, 8, 1045-53. 7. W.M. Jeffries, Med. Hypotheses, 1998, 51, 114-4.

1. E. Friess, et al., Eur J Clin Invest, 2000, 30, Suppl 3:46-50. 2. Freeman, Scott, 2002. Biological Science. Prentice Hall; 2nd Pkg edition (December 30, 2004) . 3. C. Longscope., J. Endocrinology, 1996, , Suppl S125-S127. 4. J. Herbert, Lancet, 1995 345, 1193-1194. 5. A. Michael, et al., Biol. Psychiatry, 2000, 48, 989-95. 6. C.R. Dequet and D.J. Wallace, Current Opin. Ivest. Drugs, 2001, 8, 1045-53. 7. W.M. Jeffries, Med. Hypotheses, 1998, 51, 114-4.