Cushing's syndrome laboratory findings: Difference between revisions
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When Cushing's is suspected, either a [[dexamethasone suppression test]] (administration of dexamethasone and frequent determination of cortisol and ACTH level), or a 24-hour urinary measurement for cortisol offer equal detection rates.<ref>Raff H, Findling JW. ''A physiologic approach to diagnosis of the Cushing's syndrome.'' Ann Intern Med 2003;138:980-91. PMID 12809455</ref> Dexamethasone is a [[glucocorticoid]] and simulates the effects of cortisol, including [[negative feedback]] on the [[pituitary gland]]. When dexamethasone is administered and a blood sample is tested, high cortisol would be indicative of Cushing's syndrome because there is an ectopic source of cortisol or ACTH (eg: adrenal adenoma) that is not inhibited by the dexamethasone. A novel approach, recently cleared by the US FDA, is sampling cortisol in [[saliva]] over 24 hours, which may be equally sensitive, as late night levels of salivary cortisol are high in Cushingoid patients. Other pituitary hormone levels may need to be ascertained. Performing a [[physical examination]] to determine any [[visual field]] defect may be necessary if a pituitary lesion is suspected, which may compress the [[optic chiasm]] causing typical bitemporal hemianopia | When Cushing's is suspected, either a [[dexamethasone suppression test]] (administration of dexamethasone and frequent determination of cortisol and ACTH level), or a 24-hour urinary measurement for cortisol offer equal detection rates.<ref>Raff H, Findling JW. ''A physiologic approach to diagnosis of the Cushing's syndrome.'' Ann Intern Med 2003;138:980-91. PMID 12809455</ref> Dexamethasone is a [[glucocorticoid]] and simulates the effects of cortisol, including [[negative feedback]] on the [[pituitary gland]]. When dexamethasone is administered and a blood sample is tested, high cortisol would be indicative of Cushing's syndrome because there is an ectopic source of cortisol or ACTH (eg: adrenal adenoma) that is not inhibited by the dexamethasone. A novel approach, recently cleared by the US FDA, is sampling cortisol in [[saliva]] over 24 hours, which may be equally sensitive, as late night levels of salivary cortisol are high in Cushingoid patients. Other pituitary hormone levels may need to be ascertained. Performing a [[physical examination]] to determine any [[visual field]] defect may be necessary if a pituitary lesion is suspected, which may compress the [[optic chiasm]] causing typical bitemporal hemianopia. | ||
==References== | ==References== | ||
Revision as of 20:57, 23 August 2012
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
Laboratory Findings
When Cushing's is suspected, either a dexamethasone suppression test (administration of dexamethasone and frequent determination of cortisol and ACTH level), or a 24-hour urinary measurement for cortisol offer equal detection rates.[1] Dexamethasone is a glucocorticoid and simulates the effects of cortisol, including negative feedback on the pituitary gland. When dexamethasone is administered and a blood sample is tested, high cortisol would be indicative of Cushing's syndrome because there is an ectopic source of cortisol or ACTH (eg: adrenal adenoma) that is not inhibited by the dexamethasone. A novel approach, recently cleared by the US FDA, is sampling cortisol in saliva over 24 hours, which may be equally sensitive, as late night levels of salivary cortisol are high in Cushingoid patients. Other pituitary hormone levels may need to be ascertained. Performing a physical examination to determine any visual field defect may be necessary if a pituitary lesion is suspected, which may compress the optic chiasm causing typical bitemporal hemianopia.
References
- ↑ Raff H, Findling JW. A physiologic approach to diagnosis of the Cushing's syndrome. Ann Intern Med 2003;138:980-91. PMID 12809455