Adrenocorticotropic Hormone Stimulation Test (ACTH Stimulation Test, Corticotropin Stimulation, Cortisol Stimulation Test, Cortrosyn Stimulation Test, Cosyntropin Test)


Test Description

The hypothalamus secretes corticotropin-releasing hormone. This hormone stimulates
the secretion of adrenocorticotropic hormone (ACTH) by the anterior pituitary
gland. ACTH, in turn, causes the adrenal cortex to release the glucocorticoid hormone
cortisol. Problems occurring in the adrenal cortex are considered “primary”
disorders, whereas those occurring in the anterior pituitary gland are known as “secondary”
disorders. It is important to determine whether a patient’s problem is of a
primary or a secondary nature.
Various tests may be used to evaluate adrenal hypofunction through stimulation
of the adrenal glands. The most common is the rapid ACTH test, for which cosyntropin
(Cortrosyn) is administered. ACTH stimulation testing is especially valuable
in the diagnosis of Addison’s disease. If plasma cortisol levels increase after administration
of ACTH, the adrenal gland has the ability to function when stimulated and
the cause of the adrenal insufficiency would be due to a problem in the pituitary
gland. If, however, the plasma cortisol levels do not rise or increase only minimally,
the problem lies with the adrenal gland. The test can also be used to check for
recovery of the hypothalamus-pituitary-adrenal (HPA) axis during tapering of
steroids after long-term use.

Normal Values

Rise of at least 7 mcg/dL above baseline level with peak of >20 mcg/dL

Possible Meanings of Abnormal Values

Minimal or No Increase                                                                                                                        

Addison’s disease
Adrenal insufficiency
Adrenocortical tumor
Contributing Factors to Abnormal Values:
• Levels of ACTH may vary with exercise, sleep, and stress.
• Drugs that may also affect test results: amphetamines, calcium gluconate, corticosteroids,
 estrogens, ethanol, lithium carbonate, spironolactone.

Interventions/Implications

Pretest
           • Explain to the patient the purpose of the test and the need for multiple blood samples to
            be drawn.
           • Fasting and limited activity for 10 to 12 hours before the test is required.

Procedure

• A 5-mL blood sample is drawn in a collection tube containing heparin for a baseline
plasma cortisol level, labeled, and sent to the laboratory.
• Within 30 minutes of drawing the baseline cortisol level, cosyntropin (Cortrosyn) is
administered either intravenously (preferable) or intramuscularly.
• Plasma cortisol levels are drawn at 30 and 60 minutes after cosyntropin administration.
• Gloves are worn throughout the procedure.

Post test

• Apply pressure at venipuncture site. Apply dressing, periodically assessing for continued
bleeding.
• Each blood sample must be carefully labeled as to the time it was drawn, including
whether it was baseline, 30 minutes after the cosyntropin administration, or 60 minutes
after the cosyntropin administration.
• Transport the specimens to the laboratory.
• Report abnormal findings to the primary care provider.

clinical Alert                                                                                                                                          

  • When testing for HPA axis recovery during tapering of steroids, if the increase in

       cortisol is <7 mcg/dL and/or the peak cortisol value is <20 mcg/dL, a slower

       steroid taper is recommended and the challenge test should be retried at a later date.
       

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