Cosyntropin test

Because all known therapeutic effects ofACTH can be achieved with corticosteroids, synthetic steroid hormones generally are used therapeutically instead ofACTH. A synthetic derivative of ACTH comprised of the first 24 amino acids of the natural hormone, cosyntropin ( cortrosyn, syn-acthen), is used principally in the diagnostic assessment of the HPA axis. In the standard cosyntropin test, cosyntropin is used at the considerably supraphysiological dose of 250 pg to maximally stimulate adrenocortical steroidogenesis. Cosyntropin is readily absorbed from... 

The short cosyntropin-stimulation test can be used to assess patients with suspected hypocortisolism. An increase to a cortisol level >18 mcg/dL (500 mmol/L) rules out adrenal insufficiency. 

Patients with Addison s disease have an abnormal response to the short cosyntropin-stimulation test. Plasma ACTH levels are usually 400 to 2,000 pg/mL in primary insufficiency versus normal to low (0 to 50 pg/mL) in secondary insufficiency. A normal cosyntropin-stimulation test does not rule out secondary adrenal insufficiency. 

ACTH stimulation of the adrenals will fail to elicit an appropriate response in states of adrenal insufficiency. A rapid test for ruling out adrenal insufficiency employs cosyntropin (see below). Plasma cortisol levels are measured before and either 30 minutes or 60 minutes following an intramuscular or intravenous injection of 0.25 mg of cosyntropin. A normal plasma cortisol response is a stimulated peak level exceeding 20 g/dL. A subnormal response indicates primary or secondary adrenocortical insufficiency that can be differentiated using endogenous plasma ACTH levels (which are increased in primary adrenal insufficiency and decreased in the secondary form). 

Cosyntropin is the preferred preparation for diagnostic use. The standard diagnostic test dose of 0.25 mg is equivalent to 25 units of porcine corticotropin. ACTH is rarely indicated but is available for use in doses of 10-20 units four times daily. Repository ACTH, 40-80 units, may be administered every 24-72 hours. 

Adrenal glands measurement of morning serum cortisol concentration or cosyntropin stimulation test Thyroid gland ultrasensitive determination of TSH Gonads sex hormone determinations (estradiol in women and testosterone in men) and gonadotropins... 

Adrenal glands cosyntropin stimulation test Thyroid gland ultrasensitive determination of TSH concentration... 

Cortisol levels greater than 18 to 20 mcg/dL 30 minutes after a cosyntropin-stimulation test are not useful in patients who are acutely ill. Severe infection, trauma, bums, illnesses, or surgery can increase cortisol production by as much as a factor of six, making the recognition of adrenal insufficiency in this population extremely difficult. In the critically ill, a random cortisol level below 15 mcg/dL is indicative of adrenal insufficiency, while a level greater than 34 mcg/dL suggests that adrenal insufficiency is unlikelyFor patients who fall between these two values, a poor response to corticotropin (less than... 

The short cosyntropin stimulation test can be used to assess... 

Cosyntropin, an anterior pituitary hormone (0.25 to 1 mg IM or IV), is used as a diagnostic test of adrenocortical function. 

For the treatment of suspected but unconfirmed acute adrenal insufficiency, 4 mg of dexam-ethasone sodium phosphate can be substituted for hydrocortisone, since dexamethasone does not cross-react in the cortisol assay and will not interfere with the measurement of cortisol (either basaUy or in response to the cosyntropin stimulation test). A failure to respond to cosyntropin in this setting is diagnostic of adrenal insufficiency. Often, plasma ACTH also is measured to provide information about the underlying etiology if the diagnosis of adrenocortical insufficiency is established. 

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