Cushing's Disease or Syndrome?
What's the difference between Cushing's Disease and Cushing's Syndrome?
Cushing’s syndrome is a hormonal disorder
Cortisol is a normal hormone produced in the outer portion of the adrenal glands. When functioning normally, cortisol helps the body respond to stress and change. It mobilizes nutrients, modifies the body's response to inflammation, stimulates the liver to raise blood sugar, and helps control the amount of water in the body. Cortisol production is regulated by the adrenocorticotrophic hormone (ACTH), produced in the pituitary gland. Spontaneous overproduction of cortisol in the adrenals is divided into two groups – those attributed to an excess of ACTH and those that are independent of ACTH.
Cushing’s syndrome is the term used to describe a group of symptoms that occur when a persons’ cortisol levels are too high (known as hypercortisolism) for too long. The majority of people have Cushing’s syndrome because they are regularly taking certain medicine(s) that continually add too much cortisol to the body. Doctors call this an “exogenous” (outside the body) cause of Cushing’s syndrome. Other people have Cushing’s syndrome because something is causing the adrenal gland(s) to overproduce cortisol. Doctors call this an “endogenous” (inside the body) cause of Cushing’s syndrome.
Cushing’s disease is a form of Cushing’s syndrome
Cushing’s disease is the most common form of endogenous Cushing’s syndrome. It is caused by a tumor in the pituitary gland that secretes excessive amounts of a hormone called Adrenocorticotropic hormone, or ACTH. Fortunately, this type of tumor is typically benign. Unlike a cancerous (malignant) tumor, a benign tumor stays in its original location and will not spread. After you are diagnosed with Cushing’s syndrome, it is important that your doctor continues the diagnostic process to determine the cause of hypercortisolism.
From the message boards It is not only a tumor that causes Cushings Disease---many of us have the rarer form of this rare disease which is Pituitary Hyperplasia. It also causes CD and may be nodular (shown on MRI s a tumor) or dispersed (meaning spread throughout the gland).
How a pituitary tumor causes Cushing’s disease
ACTH is a hormone produced in your pituitary gland. ACTH travels to your adrenal glands and signals them to produce cortisol.
Pituitary adenomas are benign tumors of the pituitary gland which secrete increased amounts of ACTH, causing excessive cortisol production. Most patients have a single adenoma. First described in 1912 by neurosurgeon Harvey Cushing in his book The Pituitary Body and its Disorders, Cushing’s disease is the most common cause of spontaneous Cushing’s syndrome, accounting for 60 to 70 percent of cases.
If a person has Cushing’s disease, it means that a group of abnormal cells has built up in the pituitary gland to form an ACTH-producing pituitary tumor. These abnormal cells produce ACTH, just as normal pituitary gland cells do—only far too much. The excess ACTH travels to adrenal glands. The adrenal glands are then bombarded with signals to produce more and more cortisol. As a result, the adrenal glands continuously secrete too much cortisol.
Ectopic ACTH Syndrome
Some benign or malignant (cancerous) tumors that arise outside the pituitary can produce ACTH. This condition is known as ectopic ACTH syndrome. Lung tumors cause more than 50 percent of these cases. Other less common types of tumors that can produce ACTH are thymomas, pancreatic islet cell tumors, and medullary carcinomas of the thyroid.
An abnormality of the adrenal glands such as an adrenal tumor may cause Cushing's syndrome. Most of these cases involve non-cancerous tumors called adrenal adenomas, which release excess cortisol into the blood.
Adrenocortical carcinomas, or adrenal cancers, are the least common cause of Cushing's syndrome. Cancer cells secrete excess levels of several adrenal cortical hormones, including cortisol and adrenal androgens. Adrenocortical carcinomas often cause very high hormone levels and rapid onset of symptoms.
Familial Cushing's syndrome
Most cases of Cushing's syndrome are not genetic. However, some individuals may develop Cushing's syndrome due to an inherited tendency to develop tumors of one or more endocrine glands. In Primary Pigmented Micronodular Adrenal Disease, children or young adults develop small cortisol-producing tumors of the adrenal glands. In Multiple Endocrine Neoplasia Type I (MEN I), hormone secreting tumors of the parathyroid glands, pancreas and pituitary occur. Cushing's syndrome in MEN I may be due to pituitary, ectopic or adrenal tumors.
Obesity, type 2 diabetes, poorly controlled blood glucose (blood sugar levels), and high blood pressure may increase the risk of developing this disorder.