What is adrenocorticotropic hormone?
Adrenocorticotropic hormone or ACTH is produced by pituitary gland in the brain and travels in the blood to the adrenal glands sitting on the kidneys. The hormone acts on the outer part of each adrenal glance, known as the adrenal cortex, causing the adrenal hormones called glucocorticoids, mineralocorticoids and sex hormones. Glucocorticoids such as cortisol affect how the body metabolizes protein and carbohydrates, while mineralocorticoids affect the balance of liquid and electrolytes. ACTH secretion increases under stress conditions. The hormone relaxing corticotropin then travels to the pituitary and stimulates it to create more adrenocorticotropic hormones, which increases the adrenal secretion. Higher levels of glucocorticoids in the blood inhibit the production of Horticotropin releasing hormone, which means less pituitary stimulation and subsequent decrease in adrenocorticotropic hormone. This type of system is known as a loop of negative feedback. Cortisol levels are usually also measured to create a complete picture of what the childrenis. The lack of adrenocorticotropic hormone may be the result of the adrenal tumor or insufficiently active pituitary gland and also occurs in some people taking steroid drugs.
If there is an excess of adrenocorticotropic hormone, this may indicate the presence of cancer producing hormones in the lungs. Alternatively, this could mean that one has Addison's disease where the adrenal glands are damaged or Cushing's disease, in which a benign tumor is formed in the pituitary and produces adrenocorticotropic hormone. Addison's disease is usually treated with a lifelong replacement of the missing adrenal glands, while in Cushing's surgery it is used to remove the pituitary tumor.
What is called a test stimulation of adrenocorticotropic hormone can be used to diagnose Addison's disease. The short version of the test shows the injection of the substance known as tetracosacside, which is a synthetic copy of adrenocorticotropichormone. Cortisol levels in the blood are measured after about half an hour and compared to the levels taken before the test. In the longer version of the test, cortisol levels are measured regularly within 24 hours. If the adrenal glands work normally, they should respond to tetracosacside by creating more cortisol, so if the levels do not increase, it may mean the adrenal damage observed in Addison's disease.