Cortisol and corticotropin, or ACTH, are hormones that are produced in different parts of the body. The adrenal glands secrete cortisol while the pituitary gland is responsible for ACTH production. However, production of cortisol depends on the hypothalamus, pituitary and adrenal glands. Because of this, pituitary dysfunction can lead to an imbalance in ACTH, which could then result in impaired cortisol production.
Relationship
ACTH controls cortisol production. The hypothalamus and pituitary gland are both involved in cortisol production and are found in the brain. Corticotropin releasing hormone, or CRH, is released by the hypothalamus and it stimulates the pituitary gland to secrete ACTH. The released ACTH then induces the adrenal glands to produce cortisol.
Functions
Under normal circumstances, cortisol controls the amount of glucose in the blood by stimulating the liver to produce more glucose. It also regulates blood pressure--the force blood exerts on the arterial walls as it flows through the arteries. Other functions of cortisol include helping the body respond to injury, stress and illness. It also controls the body's response to inflammation.
Disorders
Cushing's disease is a hormonal disorder characterized by high levels of cortisol in the blood. It is caused by over-production of ACTH. This disease is different from Cushing's syndrome--a hormonal disorder in which the adrenal glands make too much cortisol. In Cushing's syndrome, ACTH does not play a role in cortisol overproduction. Adrenal tumors or taking too much cortisol-like drugs may lead to Cushing's syndrome. According to the National Adrenal Diseases Foundation, Dr. Harvey Cushing linked high cortisol production by the adrenal glands to a dysfunction of the pituitary gland in 1932.
Secondary adrenal insufficiency--a disease in which cortisol levels are low--occurs when the pituitary gland produces low amounts of ACTH.
Causes
ACTH secreting tumors in the pituitary gland can lead to excessive production of cortisol and cause Cushing's disease. The National Adrenal Diseases Foundation says that tumors in other areas of the body, such as the pancreas, lungs and thymus gland also secrete ACTH. This disorder is called ectopic ACTH syndrome and it can lead to high cortisol levels.
When the body is exposed to low ACTH levels, the adrenal glands produce insufficient amounts of cortisol and secondary adrenal insufficiency occurs. Low blood flow to the pituitary gland can cause this disorder. It may also occur due to surgical removal of the pituitary gland or parts of the hypothalamus.
Treatment
The National Endocrine and Metabolic Diseases Information Service explains that surgery, chemotherapy and radiation may be used to remove or eliminate ACTH secreting tumors in Cushing's disease. Treatment for secondary adrenal insufficiency involves replacing cortisol by administering cortisol-like drugs such as hydrocortisone.
Expert Insight
According to the National Endocrine and Metabolic Diseases Information Service, Cushing's disease affects women five times more than men. Ectopic ACTH syndrome on the other hand, affects men three times more than women.
References
- The Merck Manuals Online Medical Library: Addison's Disease
- The Merck Manuals Online Medical Library: Cushings Syndrome
- National Endocrine and Metabolic Diseases Information Service: Adrenal Insufficiency and Addison's Disease
- National Adrenal Diseases Foundation: Adrenal Diseases - Cushing's Syndrome
- National Endocrine and Metabolic Diseases Information Service: Cushing's Syndrome
