Serum ACTH

What is endogenous ACTH?

serum_acth-1ACTH (adrenocorticotropic hormone) is a hormone produced by the pituitary gland. The term endogenous simply refers to the ACTH that is produced by the animal itself (as opposed to synthetic ACTH, which is used for diagnostic testing purposes).

"ACTH regulates the production of cortisol..."

ACTH regulates the production of cortisol (a stress hormone) by the adrenal glands and its concentration can be measured in the blood.

If the level of cortisol in the blood is low, the pituitary gland will be stimulated to secrete ACTH. In turn, an increased blood cortisol level will reduce the amount of ACTH being secreted by the pituitary in a negative feedback system.

What can the measurement of ACTH tell us?

If Cushing's disease (hyperadrenocorticism) is caused by excessive pituitary production of ACTH, an increased concentration of ACTH will be found in the blood.

serum_acth-2If Cushing's disease is due to an adrenal tumor, or when Cushing's disease is caused by cortisol containing medications, the amount of ACTH in the blood is decreased (due to the negative feedback system described above).

Therefore, in some cases of Cushing's disease the measurement of endogenous ACTH will allow us to make a distinction between the different types of Cushing's disease.

Can endogenous ACTH alone diagnose Cushing's disease?

No. In health and disease, ACTH is released from the pituitary in an episodic or pulsatile (e.g. up and down) fashion. Therefore, the concentrations of ACTH found both in health and with the different types of Cushing's disease might overlap and not allow a clear differentiation of the cause of the disease. Additionally, stress may also cause periodic increases in endogenous ACTH concentrations. Thus, endogenous ACTH values are most useful in the investigation of the type of Cushing's disease that is present once the Cushing's syndrome has been confirmed by the use of other laboratory tests.

Related Tags

acth, disease, cushing, endogenous, pituitary, hormone, cortisol, serum, gland, amount, negative, concentration, health, concentrations, adrenal, feedback, increased, stress, purposes, diagnostic, synthetic, opposed, refers, simply, regulates, animal, adrenocorticotropic, ruotsalo, kristiina, laboratory, increases, investigation, syndrome, confirmed, dvsc, copyright, modified, permission, license, additionally, lifelearn, margo, tant, 2009, acvp, excessive, hyperadrenocorticism, tumor, medications, secreted, reduce, glands, stimulated, secrete, decreased

Looking to learn more?

We also offer free, instant access to over 1,500 related articles on your pet's health including preventive medicine, common and not so common diseases, and even informative case studies. We encourage you to read any of these popular articles below or search our extensive pet health library.

Most Popular Articles

About our approach to exceptional pet health care

At VCA Animal Hospitals, our veterinarians take you and your pet's health seriously. With over 600 hospitals and 1,800 fully qualified, dedicated and compassionate veterinarians, we strive to give your pet the very best in medical care. We understand your pet is an extension of you, and appreciate the opportunity to share in providing exceptional pet care and quality of life.

* Free initial health exam for new clients only. Not to be combined with any other offer. Not good toward boarding, grooming, prescription and non-prescription medication, and retail items. Not good toward emergency and/or specialty veterinary services. Coupon good for up to two pets (dogs or cats only) per household. Redeemable only at a general practice VCA Animal Hospital. For pet owners who are aged 18 and older.

If you are a new client, you can get a free first exam* on your first visit.

Free First Exam

Get to know us by visiting one of our neighborhood hospitals.

Locate a Hospital