Cho-Cho & Sophia

Cushing syndrome #1
is a disorder that occurs when your body is exposed to high levels of the hormone cortisol.
It may also occur if you take too much cortisol or other steroid hormones.

Cushing syndrome may be caused by taking too much corticosteroid medications, such as prednisone and prednisolone.
These drugs are used to treat conditions such as asthma and rheumatoid arthritis.
Other people develop Cushing syndrome because their bodies produce too much cortisol, a hormone normally made in the adrenal gland.
Causes of too much cortisol are:

• Cushing's disease, when the pituitary gland makes too much of the hormone ACTH. ACTH then signals the adrenal glands to produce cortisol. Tumor of the pituitary gland may cause this condition.
• Tumor of the adrenal gland
• Tumor elsewhere in the body that produces cortisol
• Tumors elsewhere in the body that produce ACTH (such as the pancreas, lung, and thyroid)

Exams and Tests
Blood sugar and white blood cell counts may be high. Potassium level may be low.

Laboratory tests that may be done to diagnose Cushing syndrome and identify the cause are:
•Serum cortisol levels
•Salivary cortisol levels
•Dexamethasone suppression test
•24-hour urine for cortisol and creatinine
•ACTH level
•ACTH (cosyntropin) stimulation test

Tests to determine the cause or complications may include:
•Abdominal CT
•ACTH test
•Pituitary MRI
•Bone density, as measured by dual x-ray absorptiometry (DEXA)
High cholesterol, including high triglycerides and low high-density lipoprotein (HDL) may also be present.


Cushing’s disease #2
is a condition in which the pituitary gland releases too much adrenocorticotropic hormone (ACTH).
The pituitary gland is an organ of the endocrine system.

Cushing's disease is caused by a tumor or excess growth (hyperplasia) of the pituitary gland.
This gland is located at the base of the brain.
People with Cushing's disease have too much ACTH. ACTH stimulates the production and release of cortisol, a stress hormone.
Too much ACTH means too much cortisol.
Cortisol is normally released during stressful situations.
It controls the body's use of carbohydrates, fats, and proteins and also helps reduce the immune system's response to swelling (inflammation).

Exams and Tests
Tests are done to confirm there is too much cortisol in the body, then to determine the cause.

These tests confirm too much cortisol:
•24-hour urine cortisol
•Dexamethasone suppression test (low dose)

These tests determine cause:
•Blood ACTH level
•Brain MRI
•Corticotropin-releasing hormone test, which acts on the pituitary gland to cause the release of ACTH
•Dexamethasone suppression test (high dose)
•Petrosal sinus sampling - measures ACTH levels in the veins that drain the pituitary gland.


Cushing syndrome - exogenous #3
Exogenous Cushing syndrome is a form of Cushing syndrome that occurs in people taking glucocorticoid (also called corticosteroid) hormones, such as prednisone.

Causes
Exogenous means caused by something outside the body.
Exogenous Cushing syndrome occurs when a person takes human-made (synthetic) glucocorticoids, such as prednisone or dexamethasone, for treatment purposes (for example, to treat asthma).
In Cushing syndrome, the adrenal glands produce too much of certain hormones, such as cortisol.

Exams and Tests
In people who use cortisone, prednisone, or other corticosteroids, the following test results may suggest exogenous Cushing syndrome:
•Low ACTH level
•Low cortisol level
•No response to a cosyntropin stimulation test
•Higher than normal fasting glucose
•Low blood potassium level
•Low bone density, as measured by dual x-ray absorptiometry (DEXA)
•High cholesterol, particularly high triglycerides and low high-density lipoprotein (HDL)

A method called high performance liquid chromatography (HPLC) can show high levels of the suspected medication in the urine.


Cushing syndrome due to adrenal tumor #4
is an endocrine system disorder that occurs when there is a tumor of the adrenal gland releasing excess amounts of the hormone cortisol.

Causes
Cushing syndrome is caused by constant, high levels of the steroid hormone cortisol.
A tumor on one of the adrenal glands causes about 15% of all cases of Cushing syndrome. Adrenal tumors release cortisol.
Adrenal tumors may be noncancerous (benign) or cancerous (malignant).

Noncancerous tumors that may cause Cushing syndrome include:
•Adrenal adenomas
•Micronodular hyperplasia

Cancerous tumors that may cause Cushing syndrome include:
•Adrenal carcinomas
Adrenal tumors are rare. They may develop in anyone at any age, but are much more common in adults.
They are found in women more often than men.

Exams and Tests
Tests to confirm Cushing syndrome:
•24-hour urine sample to measure the following:
◦Urine cortisol
◦Urine creatinine
•Dexamethasone suppression test
•Serum cortisol levels

Tests to determine cause:
•Abdominal CT
•ACTH
•High-dose dexamethasone suppression test

Other findings may include:
•High cholesterol
•High fasting glucose
•Low bone density, seen by dual x-ray absorptiometry (DEXA)
•Low serum potassium

Ectopic Cushing syndrome #5
is a condition in which a tumor outside the pituitary or adrenal glands produces a hormone called adrenocorticotropic hormone (ACTH).

Causes
Cushing syndrome is the result of too much glucocorticoid hormones being released over a long period of time.
About 15% of Cushing syndrome cases are due to ectopic Cushing syndrome.

Ectopic Cushing syndrome is caused by tumors that release adrenocorticotropic hormone (ACTH).

Other causes of Cushing syndrome are:
•Excess release of ACTH by the pituitary gland
•Long-term use of corticosteroid drugs (commonly used to treat conditions such as rheumatoid arthritis and asthma)
•Tumor of the adrenal gland

Tumors that can, in rare cases, release ACTH include:
•Islet cell tumors of the pancreas
•Medullary carcinoma of the thyroid
•Small cell tumors of the lung
•Tumors of the thymus gland

Exams and Tests
Tests that may be done include:
•24-hour urine for cortisol and creatinine
•Blood tests to check ACTH, cortisol, and potassium levels
•Dexamethasone suppression test
•Fasting glucose
•MRI and CT scans to find tumors


Cortisol level (Serum cortisol) #6
A cortisol level is a blood test that measures the amount of cortisol,
a steroid hormone produced by the adrenal cortex.

Why the Test is Performed
The test is done to check for increased or decreased cortisol production. Cortisol is a steroid hormone released from the adrenal gland in response to ACTH, a hormone from the pituitary gland in the brain.

Cortisol affects many different body systems. It plays a role in:

•Bone
•Circulatory system
•Immune system
•Metabolism of fats, carbohydrates, and protein
•Nervous system
•Stress responses
Different diseases, such as Cushing's disease and Addison's disease, can lead to either too much or too little production of cortisol.
Cortisol levels are often measured to help diagnose these conditions and to evaluate how well the pituitary and adrenal glands are working.

What Abnormal Results Mean
Higher than normal levels may indicate:
•Adrenal tumor
•Cushing's syndrome
•Ectopic ACTH-producing tumors

Lower than normal levels may indicate:
•Addison's disease
•Hypopituitarism

Other conditions under which the test may be performed:
•Acute adrenal crisis
•Ectopic Cushing's syndrome
•Pituitary Cushing's (Cushing's disease)


參考資料
1. MedlinePlus - Cushing syndrome
2. MedlinePlus - Cushing's disease
3. MedlinePlus - Cushing syndrome - exogenous
4. MedlinePlus - Cushing syndrome due to adrenal
5. MedlinePlus - Ectopic Cushing syndrome
6. MedlinePlus - cortisol level