ACTH or Corticotropin test
Patient preparation
The doctor may request that the person fast the night before. The blood sample is typically taken around 8 am.
The reason for the test request
This test helps diagnose adrenal gland and pituitary diseases, such as Cushing’s syndrome, Cushing’s disease, Addison’s disease, adrenal tumors and pituitary tumors; or when a person has symptoms related to overproduction or lack of cortisol; It is requested when the doctor suspects that a person has a hormonal imbalance that can cause problems in the pituitary or adrenal glands.
Explanation about the test
This test measures the amount of adrenocorticotropic hormone (ACTH) in the blood. ACTH is a hormone that stimulates the production of cortisol. Cortisol is an important steroid hormone for regulating sugar, protein and fat metabolism, by suppressing the body’s immune response and maintaining blood pressure. Normally, ACTH levels increase when cortisol is low and decrease when cortisol is high.
In what conditions is the test increased?
Cushing’s disease, Addison’s disease, or a tumor producing abnormal ACTH and stress increase ACTH. Some tumors outside the pituitary gland in places like the lungs can increase cortisol concentration by producing ACTH.
Under what conditions is the test reduced?
Adrenal tumors, steroid drugs, or hypopituitarism can increase ACTH.
Supplementary tests
Cortisol, Cortrosyn (ACTH) stimulation test, Dexamethasone suppression test
Drug interactions
Some drugs including amphetamine, insulin, levodopa, metoclopramide and RU 486 can increase ACTH levels.
Additional information
Too much cortisol can cause obesity where most of the weight is on the trunk, not the arms and legs; round face; fragile and thin skin; purple lines on the abdomen; muscle weakness; acne; and increase body hair. These are often accompanied by findings such as high blood pressure, low potassium, high bicarbonate, high glucose levels, and sometimes diabetes.
Insufficient production of cortisol may cause muscle weakness; fatigue; weight loss; Increased skin pigmentation, even in areas that are not exposed to sunlight; and loss of appetite. These are often accompanied by findings such as hypotension, low blood sugar, low sodium, high potassium, and high calcium.
ACTH and cortisol concentrations vary throughout the day. Naturally, ACTH is at its highest level in the morning and at its lowest level at night. It stimulates the production of cortisol, which follows the same daily pattern, but after ACTH rises, it will rise and fall to its lowest level late at night. Diseases that affect the production of ACTH and cortisol often disrupt these daily changes.
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