Iatrogenic Cushing's Disease

Cushing̵7;s disease is also known as hyperadrenocorticism, or the overproduction of adrenal hormone, corticosteroids. Hyperadrenocorticism can be caused by natural phenomenon; however, most often it is caused by the overuse of corticosteroids in veterinary medicine. This is referred to as iatrogenic Cushing̵7;s disease. Veterinarians and human physicians alike use corticosteroids for a variety of purposes with the main goal being to suppress the immune system. Common uses include treating allergies, rheumatoid arthritis and controlling autoimmune diseases in both dogs and humans.

  1. Cause

    • In iatrogenic Cushing̵7;s disease cases, the patient has usually been receiving repeated doses of glucocorticosteroids as a treatment protocol for an underlying condition. These treatments are administered either orally or through intramuscular injections. The body continues to produce naturally occurring ACTH, or adrenocorticotropin hormone, which then stimulates the adrenal gland to produce cortisol. The external source of corticosteroids also stimulates the adrenal gland to produce cortisol, resulting in an extremely high level of cortisol circulating in the body. The excess cortisol then impacts the pituitary gland and reduces the amount of ATCH it produces naturally.

    Symptoms

    • Typical symptoms of iatrogenic Cushing̵7;s disease include increased thirst, rapid weight gain (especially in the torso and facial area), excessive sweating, thinning of the skin, hair thinning, susceptibility to fungal infections, insomnia, increased frequency in urinating, high blood pressure and increased blood sugar. The hallmark sign of Cushing̵7;s disease is described as a patient having a ̶0;moon face,̶1; or an overly rounded face due to the increase of weight around the central sections of the body. Both the upper and lower extremities tend to be exempt from the weight gain phenomenon in iatrogenic Cushing̵7;s disease patients.

      Dogs experiencing iatrogenic Cushing's disease will exhibit similar symptoms, most notably torso and facial swelling, increased water consumption and urination, thinning of the coat, and a higher susceptibility to fungal infections.

    Diagnosis

    • Diagnosing iatrongenic Cushing̵7;s disease works the same way for both dogs and humans. It involves conducting a dexamethasone suppression test in which dexamethasone, a glucocorticosteroid, is administered to the patient. A tested blood sample will indicate the presence of cortisol. High cortisol values indicate a positive Cushing̵7;s test and treatment should begin immediately.

    Treatment

    • Treatment for iatrogenic Cushing̵7;s disease is straightforward. Tapering off the external glucocorticosteroids slowly allows the body to slowly resume its normal balance of ACTH and cortisol production.

    Prevention/Solution

    • Prevention is the key to controlling this disease. Iatrogenic Cushing's disease is a direct result of the long-term administration of external corticosteroids to patients. Whenever possible, doctors and veterinarians will explore other treatment avenues before administering a corticosteroid therapy.