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Cortisol Saliva ELISA

Key Features and Values

– Same sample type can be used across all assays to simplify inclusion into routine serology work-up
– Ready to use reagents reduces hands-on time for assay preparation
– Long shelf life provides a cost-effective solution by reducing wastage due to expired kits
– Suitable for inclusion on automated plate systems simplifies scale-up of test volume
– Supported by a complete panel of assays for supporting treatment monitoring of several forms of hormonal dysfunctions
– Suitable for use in a wide range of areas including sports medicine, paediatrics, occupational health, veterinary medicine, sleep disturbance, stress monitoring and hormone replacement therapy

Product Description

Competitive immunoenzymatic colorimetric method for the quantitative determination of Cortisol concentration in saliva. Cortisol Saliva ELISA kit is intended for laboratory use only.

Scientific Description
Cortisol is a steroid hormone synthesised from cholesterol in the zona fasciculata of the adrenal cortex.  Approximately 90% of cortisol in plasma is protein-bound to an α2-globulin, cortisol-binding-globulin (CBG), also known as transcortin.  The non-protein bound free cortisol is the biologically active hormone1.  In saliva, cortisol mainly appears in the free unbound form where its concentration is approximately two thirds of the unbound serum level.  About 15% of salivary cortisol is bound to transcortin, a normal component of uncontaminated saliva2.  Salivary cortisol concentrations are independent of saliva flow rate3.  In various clinical conditions CBG concentration, and thereby total serum cortisol concentration, changes.  Pregnancy and the use of oral contraceptives and oestrogens increase CBG concentration 2-3 times.  Additionally, in certain liver and kidney diseases and in various catabolic conditions, CBG levels decrease resulting in decreased serum cortisol concentrations while the unbound fraction is said to remain constant2.
Cortisol secretion from the adrenal gland is mainly controlled by the anterior pituitary hormone, adrenocorticotropic hormone (ACTH).  ACTH is in turn controlled by corticotropin-releasing hormone from the hypothalamus.  Three major factors are involved in the control of the hypothalamic-pituitary-adrenal (HPA) axis and thereby of cortisol: circadian rhythm, negative feedback and stress levels1.  In normal subjects, cortisol levels begin to rise at 3–4 a.m. and reach a peak at 7–9 a.m., with levels falling for the rest of the day4.  Whereas in healthy individuals late night levels are undetectable, patients with hyper function of the adrenal lose normal circadian rhythm and have detectable levels of cortisol at midnight5.
Cortisol determinations are used in the assessment of adrenocortical function and other disturbances of the HPA axis.  Measurement of salivary cortisol is an accurate method to assess the biologically active plasma free cortisol6. Measuring midnight salivary cortisol is an easy and non-invasive means of diagnosing diseases of cortisol imbalance such as Cushing’s syndrome.  Salivary cortisol is most useful as the initial test when Cushing’s syndrome is suspected and for periodic patient monitoring after pituitary surgery for Cushing’s7,8.  There is a large overlap of cortisol values at 9 a.m. between patients with Cushing’s syndrome and normal subjects, and therefore cortisol determination in the morning alone rarely allows discrimination between the two groups.  In contrast to levels measured in the morning, studies have shown that midnight levels provide 100% sensitivity in detecting the disease9.
Publications

1. David W., The Immunoassay Handbook. Third Edition. D.Wild (Ed.) Published by Elsevier Ltd. 2005.
2. Aardal, E. and Holm, A-C., ‘Cortisol in saliva – reference ranges and relation to cortisol in serum’. Eur J Clin Chem Clin Biochem, 33, 1995, 927-932.
3. Lewis JG., ‘Steroid analysis in saliva: an overview’. Clin Biochem Rev, 27, 2006, pp139-146.
4. Rossi GP., Seccia TM. and Pessina AC., ‘Clinical use of laboratory tests for the identification of secondary forms of arterial hypertension’. Crit Rev Clin Sci, 44(1), 2007, pp 1-85.
5. Nieman LK., Biller BMK., Findling JW., Newell-Price J., Savage MO., Stewart PM., and Montori VM., ‘The diagnosis of Cushing’s syndrome: an endocrine society clinical practice guideline’. J Clin Endocrinol Metab, 93, 2008, pp 1526-1540.
6. Yaneva M., Mosnier-Pudar H., Dugue M-A., Grabar S., Fulla Y. and Bertagna X., ‘Midnight salivary cortisol for the initial diagnosis of Cushing’s syndrome and various causes’. J Clin Endocrinol Metab, 89(7), 2004, pp 3345-3351.
7. Raff, H., ‘Cushing’s syndrome: diagnosis and surveillance using salivary cortisol’. Pituitary, 15, 2012, pp 64-70.
8. Raff, H., ‘Update on late-night salivary cortisol for the diagnosis of Cushing’s syndrome: methodological considerations’. Endocrine, 44, 2013, pp 346-349.
9. Raff, H., ‘Late-night salivary cortisol as a screening test for Cushing’s syndrome’. J Clin Endocrinol Metab, 83(8), 1998, pp 2681-2686.

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Code: DKO020
Clinical Area:
Incubation: 60+15 min
Sensitivity: 0,12 ng/mL
Classification: IVD, CE
Number of Tests: 96
Sample Type: Saliva
Sample Volume: 25 μL
Assay Range: 0.5-100 ng/mL