Cortisol is a glucocorticoid produced by the adrenal cortex in response to adrenocorticotropic hormone (ACTH). It is secreted with a circadian periodicity, and peaks just prior to waking in the morning. Cortisol is often elevated in major depressive disorder, certain forms of hypertension, stress, AIDS, and in the visceral fat of obese individuals. Cortisol can be measured in many matrices including blood, urine, and saliva. In serum, approximately 90-95% of cortisol is bound to proteins. Urinary cortisol is not bound to proteins, but its levels are dependent on glomerular and tubular function. In saliva, approximately 67% of cortisol is unbound. There is generally good correlation between cortisol measurements in saliva and serum. Cayman"s Cortisol ELISA Kit is a competitive assay that can be used for quantification of cortisol in urine, plasma, and other sample matrices. The assay has a range from 6.6-4,000 pg/ml and a sensitivity (80% B/B0) of approximately 35 pg/ml.NOTE: Due to an approximate 15% cross-reactivity with dexamethasone, this kit may not be suitable for use with samples that contain high concentrations of dexamethasone, such as those collected during a dexamethasone suppression test.