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|Method & Line||Sample & Target||Product||Package Info|
|IMMUNOgen - Immunoassays||Plasma,Serum||Cortisol||Tests per Package: 100|
|IMMUNOgen||The Eclectica Cortisol assay for the Eclectica and Eclectica TiCA analysers has been designed for the quantitative determination of Cortisol in human serum and heparinized plasma. The method can be used without dilution for samples containing 2.0 to 600 ng/ml of Cortisol (5.52 – 1658 nmol/l).||Code: 1703900||Package: 2 x 50|
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The Eclectica Cortisol assay for the Eclectica analyzers has been designed for the quantitative determination of Cortisol in human serum and heparinized plasma. The method can be used without dilution for samples containing 2.0 to 600 ng/ml of Cortisol (5.52–1658 nmol/l).
Cortisol is the principal glucocorticoid in the human: its systematic name is 4-Pregnene-11β, 17α,21-triol-3,20-dione and it is also known as 17-hydroxycorticosterone or hydrocortisone.
Cortisol is released into the circulation from the cortex of the adrenal gland (the zonae fasciculata and reticularis) where it is synthesised from cholesterol. The synthesis and secretion of cortisol is closely controlled by the pituitary adrenocorticotropic hormone (ACTH); increased ACTH causes blood cortisol levels to rise, decreased ACTH causes blood cortisol levels to fall. ACTH is also the trophic hormone for the zonae fasciculata and reticularis. The first step in the synthetic pathway, the conversion of cholesterol to pregnenolone, is rate limiting and is the major site of ACTH action on the adrenal. ACTH secretion is, in turn, controlled by hypothalamic corticotropin releasing hormone (CRH), also known as corticotropin releasing factor (CRF). CRH stimulates the secretion of ACTH (1, 2, 3).
The neuroendocrine control of cortisol secretion is effected by three mechanisms. Firstly, the episodic secretion and circadian rhythm of ACTH. This is the result of central nervous system events and causes the large variation in cortisol levels seen in normal individuals throughout the day - high values in the morning, low or undetectable values at night. Secondly, stress responsiveness. ACTH and cortisol levels characteristically increase in response to physical stress such as hypoglycemia. The stress response overrides circadian variations. Thirdly, feedback inhibition by cortisol. This occurs at both the hypothalamus and pituitary; high cortisol levels inhibit the release of both ACTH and CRH. This negative feedback effect can abolish the stress-induced release of CRH and ACTH.
In blood, cortisol is largely bound to serum proteins. Corticosteroid binding globulin (CBG or transcortin) binds about 75% of circulating cortisol; albumin also binds cortisol and about 10% is in the free, non protein bound form. The free fraction is thought to be metabolically active (1,2).
The half-life of cortisol in the circulation is 70-90 minutes; the major site of cortisol metabolism is the liver. Cortisol metabolites are excreted largely as glucuronides in the urine though some cortisol is also found in the urine - the so called urinary free cortisol (1,2).
Measurement of serum or plasma cortisol levels is of clinical use in a variety of conditions associated with increased or decreased cortisol secretion, such as Cushing's syndrome and primary or secondary adrenal insufficiency. In most cases single basal measurements are not useful. It is usually necessary to measure multiple samples either as part of an assessment of diurnal variation of cortisol secretion or as part of a dynamic function test. The dynamic function tests include dexamethasone suppression and stimulation tests using ACTH, insulin and CRH (1,2,3,4).
The Eclectica Cortisol assays for the Eclectica analyzers consists of:
In the Eclectica Cortisol assay, a rabbit polyclonal anti-cortisol antibody and a cortisol derivative conjugated to alkaline phosphatase are used in an enzyme immunoassay system which incorporates magnetic solid phase separation. All incubation times and reagent volumes are determined by an assay specific software protocol.
Fixed amounts of fluorescein-conjugated anti-Cortisol antibody and a Cortisol derivative conjugated to alkaline phosphatase are added to a sample, control, or standard. The reactants are incubated at 37°C. During the incubation Cortisol in the sample,control or calibrators competes with the derivative for binding to the anti-Cortisol antibody.
At the end of the incubation period anti-fluorescein coupled to a magnetic solid phase is added in excess. This rapidly and specifically binds to the Cortisol antibody complex and is sedimented in a magnetic field.
After aspirating the liquid phase and washing the solid phase, a solution of the enzyme substrate, phenolphthalein monophosphate is added to the incubation cell and the each cell incubated at 37°C. After incubation the enzyme reaction is stopped by the addition of a stop reagent and the intensity of the color developed is measured photometrically. The intensity of the color developed is inversely proportional, within the working range of the assay, to the concentration of Cortisol in the sample. The concentration of Cortisol in a patient sample or control is then determined by interpolation from a stored standard curve.
Eclectica Cortisol Reagent Kit
Eclectica Cortisol Calibration Kit
Eclectica Immunoassay Common Reagents Kit
Eclectica Immunoassay Wash Solution
Eclectica Systemic Wash Solution
1700006 Eclectica Cleaning Kit