What are the other Names for this Test? (Equivalent Terms)
- Corticotropin Blood Test
- Cosyntropin Tetracosactide Blood Test
- Synacthen Blood Test
What is Adrenocorticotropic Hormone Blood Test? (Background Information)
- The adrenocorticotropic hormone (ACTH) is a hormone released from the pituitary gland, a small endocrine gland (gland which secretes hormones) located at the base of the brain in the center.
- ACTH stimulates the release of other hormones from the adrenal gland (another hormone-releasing gland), which are located atop both the kidneys. The most important among these hormones, is a hormone called cortisol; while other hormones include aldosterone and dehydroepiandrosterone (DHEAS)
- Cortisol play an important role in the energy metabolism of most body cells and help the body resist stressors, like infection, bleeding, physical and emotional trauma. It also helps in keeping the level of glucose constant and maintains the blood pressure
- A rise or fall in the levels of hormones from the adrenal gland, especially cortisol, can cause certain imbalances in the body. The reason for this may be attributed to the pituitary gland, when there is an increased or decreased secretion of ACTH; or, it may be related to the adrenal gland, in which case the cortisol levels increase or decrease
- An Adrenocorticotropic Hormone Blood Test is performed along with cortisol levels, in order to not only detect a deficiency or excess of cortisol levels, but also to predict, if the cause is related to either the pituitary gland or the adrenal gland
What are the Clinical Indications for performing the Adrenocorticotropic Hormone Blood Test?
Following are the clinical indications for performing an Adrenocorticotropic Hormone Blood Test:
- Whenever a patient presents with clinical signs or symptoms of adrenal insufficiency, an ACTH Blood Test is ordered along with cortisol levels, to find the type of insufficiency and to also ascertain the cause of the condition (whether related to the pituitary or adrenal gland). Based on the results of these tests, further investigations are carried out, to arrive at a definitive diagnosis
- Some of the signs and symptoms of cortisol excess include:
- Truncal obesity
- Round faces
- Muscle weakness
- Thin and fragile skin
- Purple lines on abdomen
- Some of the signs and symptoms of cortisol deficiency include:
- Weight loss
- Loss of appetite
- Muscle weakness
- Increased skin pigmentation
How is the Specimen Collected for Adrenocorticotropic Hormone Blood Test?
Following is the specimen collection process for Adrenocorticotropic Hormone Blood Test:
Sample required: Blood
Process: Insertion of a needle into an arm vein.
Preparation required: The ACTH Blood Test is usually performed early in the morning, around 8.00 a.m. for better accuracy. Overnight fasting is required for this test.
What is the Significance of the Adrenocorticotropic Hormone Blood Test Result?
The significance of Adrenocorticotropic Hormone Blood Test is explained:
- Results of an ACTH Blood Test are evaluated along with cortisol levels. However, generally if ACTH levels are high, it may be due to:
- Cushing’s disease, when pituitary gland secretes excess of ACTH
- Addison disease, when the adrenal glands are underactive and do not produce enough cortisol
- Ectopic production of ACTH - as in the case of tumors of the pancreas, lungs, or thyroid gland, which produces ACTH and other hormones
- Congenital adrenal hyperplasia - a genetic disorder resulting in decreased formation of cortisol, or other hormones from the adrenal gland
- Lower levels of ACTH may be due to:
- Hypopituitarism, where there is a decreased activity of pituitary gland
- Adrenal gland tumor producing too much cortisol
- Tumor, located elsewhere in the body, which may be producing cortisol
The laboratory test results are NOT to be interpreted as results of a "stand-alone" test. The test results have to be interpreted after correlating with suitable clinical findings and additional supplemental tests/information. Your healthcare providers will explain the meaning of your tests results, based on the overall clinical scenario.
Additional and Relevant Useful Information:
Some factors may interfere with the ACTH Blood Test results. These include:
- Medications, such as estrogen, glucocorticoids, androgen, contraceptives, progesterone
- Excess salt consumption in the 24 hours period, before an ACTH Blood Test
- High levels of progesterone (a hormone involved in female menstruation cycle) in the body; especially after the first week of menstruation in women
- Recent radioisotopes scans - imaging of body parts using small amounts of radioactive chemical
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References and Information Sources used for the Article:
http://www.nlm.nih.gov/medlineplus/ency/article/003695.htm (accessed on 07/13/2014)
http://labtestsonline.org/understanding/analytes/acth/tab/test (accessed on 07/13/2014)