Cho-Cho & Sophia

Cortisol - urine ( 24-hour urinary free cortisol (UFC) ) #1
A cortisol urine test measures the amount of the steroid hormone cortisol in the urine

Why the Test is Performed
Cortisol is a steroid hormone released from the adrenal gland in response to ACTH, a hormone from the anterior pituitary gland in the brain.
Cortisol levels rise and fall during the day. Highest levels occur at about 6 a.m. to 8 a.m. and lowest levels at about midnight.

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

The test is done to determine if you have increased or decreased cortisol production.
 Different diseases, such as Cushing's disease and Addison's disease, can lead to either too much or too little production of cortisol.
Urine cortisol levels can help to diagnose these conditions.

Considerations
Factors that interfere with this test are:
•Medications, including glucocorticoids, lithium, diuretics, ketoconazole, estrogens and tricyclic antidepressants
•Severe emotional or physical stress
Note: Due to these interfering factors, the urine cortisol is often tested on three or more separate occasions to get a more accurate picture of average cortisol production.

What Abnormal Results Mean
Increased levels of urine cortisol may indicate:
•Cushing syndrome -- pituitary-independent
•Cushing's disease -- pituitary-dependent
•Pseudo-Cushing's
•Severe depression
•Tumor that releases ACTH

Decreased levels of urine cortisol may indicate:
•Addison's disease
•Hypopituitarism
•Congenital adrenal hyperplasia

The test may also be done in cases of exogenous Cushing syndrome.

Blood ACTH level ( Adrenocorticotropic hormone ) #2
An ACTH test measures ACTH, a hormone released from the anterior pituitary gland in the brain.

Why the Test is Performed
This test can help find the causes of hormone problems.
The main function of ACTH is to regulate the steroid hormone cortisol, which is released by the adrenal cortex.

What Abnormal Results Mean
Higher than normal levels of ACTH may be due to:
•Addison's disease
•Adrenoleukodystrophy (very rare)
•Congenital adrenal hyperplasia
•Cushing's disease
•Ectopic tumor producing ACTH
•Nelson's syndrome (very rare)

Lower than normal levels of ACTH may be due to:
•Cushing syndrome related to adrenal tumor
•Exogenous Cushing syndrome
•Pituitary insufficiency

Other conditions under which the test may be performed:
•Hypopituitarism
•Multiple endocrine neoplasia (MEN) I


ACTH (cosyntropin) stimulation test #3
measures how well the adrenal glands respond to the hormone ACTH.
ACTH is a hormone produced in the pituitary gland that stimulates the adrenal glands to release cortisol.

Why the Test is Performed
This test can help determine whether your adrenal and pituitary glands are normal.
It is most often used when the health care provider suspects adrenal gland disorders, such as Addison's disease or pituitary insufficiency.

What Abnormal Results Mean
This test is helpful in determining if you have:
•Acute adrenal crisis
•Addison's disease (decreased adrenal output)
•Low pituitary function
•Pituitary tumors


Dexamethasone suppression test #4
( DST; ACTH suppression test; Cortisol suppression test )
measures the response of the adrenal glands to ACTH.

Why the Test is Performed
This test is performed when the health care provider suspects that your body is producing too much cortisol.
It is done to help diagnose Cushing syndrome and identify the cause.

The low-dose test can help tell whether your body is producing too much cortisol.
The high-dose test can help determine whether the problem is in the pituitary gland (Cushing's disease).

The level of cortisol in the blood normally regulates the release of ACTH from the pituitary gland.
As blood cortisol levels increase, ACTH release decreases. As cortisol levels decrease, ACTH increases.

Dexamethasone is a human-made (synthetic) steroid that is similar to cortisol.
It reduces ACTH release in normal people. Therefore, taking dexamethasone should reduce ACTH levels and lead to decreased cortisol levels.
If your pituitary gland produces too much ACTH, you will have an abnormal response to the low-dose test, but a normal response to the high-dose test.

What Abnormal Results Mean
An abnormal response to the low-dose test may mean that you have abnormal release of cortisol (Cushing syndrome).
This could be due to:
•Adrenal tumor that produces cortisol
•Pituitary tumor that produces ACTH
•Tumor in the body that produces ACTH

The high-dose test can help tell a pituitary cause (Cushing's disease) from other causes.
Abnormal results vary based on the condition causing the problem.

Cushing syndrome caused by an adrenal tumor:
•Low-dose test: no change
•High-dose test: no change

Cushing syndrome related to an ectopic ACTH-producing tumor:
•Low-dose test: no change
•High-dose test: no change

Cushing syndrome caused by a pituitary tumor (Cushing's disease)
•Low-dose test: no change
•High-dose test: normal suppression


ACTH Test #5
ACTH levels in the blood are measured to help detect, diagnose, and monitor conditions associated with excessive or deficient cortisol in the body.
These conditions include:
• Cushing's disease: excess cortisol that is due to an ACTH-producing tumor in the pituitary gland (usually a benign tumor)
• Cushing's syndrome: refers to the symptoms and signs associated with excess exposure to cortisol.
In addition to Cushing's disease, Cushing's syndrome may be due to an adrenal tumor, adrenal hyperplasia, the use of steroid medications,
or due to an ACTH-producing tumor that is ectopic, located outside the pituitary (such as in the lungs).
• Addison's disease, primary adrenal insufficiency:
 decreased cortisol production due to adrenal gland damage
• Secondary adrenal insufficiency: decreased cortisol production because of pituitary dysfunction
• Hypopituitarism: pituitary dysfunction or damage that leads to decreased (or no) hormone production by the pituitary, including ACTH production 

Measuring both ACTH and cortisol can help to differentiate among some of these conditions
because the level of ACTH normally changes in the opposite direction to the level of cortisol.

What does the test result mean?
Changes in ACTH and cortisol are usually evaluated together.
The table below indicates the common patterns of ACTH and cortisol seen with different diseases involving the adrenal and pituitary glands.

An increased ACTH result can mean that a patient has Cushing's disease, Addison's disease, or ectopic ACTH-producing tumors.
A decreased ACTH result can be due to an adrenal tumor, steroid medication, or hypopituitarism.



參考資料
1. MedlinePlus - Cortisol - urine
2. MedlinePlus - ACTH
3. MedlinePlus - ACTH (cosyntropin) stimulation test
4. MedlinePlus - Dexamethasone suppression test
5. Lab Test Online - ACTH