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 5-HIAA

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عدد المساهمات : 20
العمر : 39
تاريخ التسجيل : 10/03/2010

مُساهمةموضوع: 5-HIAA   الجمعة 19 مارس - 4:25





Also known as: 5-hydroxyindoleacetic acid; HIAA; Serotonin metabolite
Formal name: 5-hydroxyindoleacetic acid
Related tests: Serotonin; Chromogranin A
Why Get Tested?
To help diagnose and monitor treatment for a serotonin-secreting carcinoid tumor
When to Get Tested?
When you have symptoms suggestive of a carcinoid tumor such as
flushing, diarrhea, and/or wheezing, and at intervals following
treatment
Sample Required?
A 24-hour urine sample; rarely a random urine sample
Test Preparation Needed?
You may be instructed to avoid certain foods and medications prior to this test.
The Test Sample
What is being tested?
This test measures the amount of 5-hydroxyindoleacetic acid (5-HIAA) in
the urine. 5-HIAA is a muscle stimulant and the primary metabolite of
serotonin, a hormone derived from the amino acid tryptophan. Serotonin
is produced as needed by the nervous system, mainly the brain, but also
special cells in the bronchial tubes (lungs) and gastrointestinal
tract. It helps transmit nerve impulses and constrict blood vessels,
participates in the wake-sleep cycle, and affects mood. After it is
used by the body, serotonin is broken down in the liver, and its
metabolites, including 5-HIAA, are excreted in the urine.
Ordinarily, only small varying amounts of 5-HIAA are present in the
urine. Large quantities of serotonin and 5-HIAA may be produced,
however, by some carcinoid tumors. Carcinoid tumors are slow-growing
masses that can form in the gastrointestinal tract, on the appendix,
and in the lungs. According to the American Cancer Society, there are
about 5,000 carcinoid tumors diagnosed each year in United States. Many
more of these tumors may exist, but most remain small and do not cause
any symptoms. When carcinoid tumors are discovered in asymptomatic
patients during surgical procedures performed for other reasons, they
are called "incidental" tumors. A small percentage of these tumors may
eventually grow large enough to cause obstructions in the intestines or
bronchial tubes of the lungs.
About 10% of carcinoid tumors, primarily those found in the
gastrointestinal tract, will produce enough serotonin to cause symptoms
such as flushing of the face, diarrhea, a rapid heart rate, and
wheezing, usually only after the tumor has spread to the liver. These
symptoms are referred to as carcinoid syndrome. The serotonin that
causes carcinoid syndrome may be released continuously or
intermittently and can lead to significantly increased quantities of
5-HIAA in the urine.
How is the sample collected for testing?
For the 24-hour urine collection, all of the urine should be saved for
a 24-hour period. It is best to keep the sample in cool, dark place,
such as a refrigerator.
NOTE: If undergoing medical tests makes you or someone you care for
anxious, embarrassed, or even difficult to manage, you might consider
reading one or more of the following articles: Coping with Test Pain,
Discomfort, and Anxiety, Tips on Blood Testing, Tips to Help Children
through Their Medical Tests, and Tips to Help the Elderly through Their
Medical Tests.
Another article, Follow That Sample, provides a glimpse at the collection and processing of a blood sample and throat culture.
Is any test preparation needed to ensure the quality of the sample?
Pre-sample preparation is important for accurate 5-HIAA test results.
Foods such as avocados, bananas, pineapples, plums, walnuts, tomatoes,
kiwi fruit, and eggplant can interfere with 5-HIAA measurement and
should be avoided for 3 days prior to and during urine collection.
There are also a variety of drugs that can affect the 5-HIAA test, but
you should talk to your doctor before decreasing or discontinuing any
medications.



The Test
1. How is it used?
2. When is it ordered?
3. What does the test result mean?
4. Is there anything else I should know?
How is it used?
5-HIAA may be ordered by itself or along with a blood serotonin level
to help diagnose and monitor carcinoid tumors. A 24-hour urine sample
is preferred for the 5-HIAA test because the metabolite level in the
urine can vary during the day. A random urine sample is sometimes
tested, usually along with a urine creatinine level, when a 24-hour
sample is not feasible. The random sample is not as accurate, however,
and if the excess 5-HIAA is released intermittently, then it may be
missed.


When is it ordered?
This test is primarily ordered when a patient has symptoms suggestive
of a carcinoid tumor. It may also be ordered at intervals to help
monitor the effectiveness of treatment in patients who have been
diagnosed with and treated for a serotonin-secreting carcinoid tumor.
What does the test result mean?
A significantly increased level of 5-HIAA in a 24-hour urine sample in
a patient with carcinoid syndrome symptoms is suggestive but not
diagnostic of a carcinoid tumor. In order to diagnose the condition,
the tumor itself must be located and a sample of it examined. The
doctor will frequently follow an abnormal test result with an order for
an imaging scan to help locate any tumor(s) that may be present.
A patient with symptoms may still have a carcinoid tumor even if the
concentration of 5-HIAA is normal. The patient may have a tumor that
does not secrete serotonin or one that secretes it intermittently. A
patient with no symptoms and normal levels of 5-HIAA is unlikely to
have a serotonin-secreting carcinoid tumor.
In patients who are being monitored following treatment for carcinoid
tumor, decreasing levels of 5-HIAA indicate a response to treatment,
while increasing or continued excessive concentrations indicate that
the treatment has not been successful.



Is there anything else I should know?
There are also a variety of drugs that can affect the 5-HIAA test.
Medications that can increase 5-HIAA include acetaminophen, caffeine,
ephedrine, diazepam (Valium), nicotine, glyceryl guaiacolate (an
ingredient found in some cough medicines), and phenobarbital.
Medications that can decrease 5-HIAA include aspirin, ethyl alcohol,
imipramine, levodopa, MAO inhibitors, heparin, isoniazid, methyldopa,
and tricyclic antidepressants. Patients should talk to their doctor
before decreasing or discontinuing any medications.

Common Questions
1. Are there other metabolites of serotonin?
2. Can I do the 5-HIAA urine test at home?
3. Will my results be accurate if I must continue to take my medication?
4. Are some people at a higher risk for developing a carcinoid tumor?
1. Are there other metabolites of serotonin?
Yes, the other major metabolite is 5-hydroxytryptphol (5-HTOL). This
substance is not routinely tested for but may sometimes be performed in
a ratio with the 5-HIAA test to evaluate ethyl alcohol ingestion. An
increased ratio of 5-HTOL/5-HIAA can be indicative of alcohol
consumption in both living people and postmortem.
2. Can I do the 5-HIAA urine test at home?
No, this test requires specialized equipment and must be performed in a
laboratory. Not every laboratory will perform this assay; in some
cases, your sample will need to be sent to a reference laboratory.
3. Will my results be accurate if I must continue to take my medication?
If the drug is one that can increase or decrease the amount of
serotonin and 5-HIAA, then your results may be affected. However, it is
up to your doctor and you to decide whether or not your medication can
be safely stopped prior to and during the test collection. If your
drugs must be taken, then your doctor will interpret the test results
with this in mind.



4. Are some people at a higher risk for developing a carcinoid tumor?
Anyone at any age can develop a carcinoid tumor but, according to the
American Cancer Society, the average age at diagnosis is usually about
55 to 65. Patients with a family history of multiple endocrine
neoplasia (MEN1), a genetic condition that increases a patient's risk
of developing tumors in the endocrine system glands, may be at higher
risk for developing a carcinoid tumor.































الرجوع الى أعلى الصفحة اذهب الى الأسفل
lisy
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عدد المساهمات : 31
العمر : 46
تاريخ التسجيل : 04/06/2010

مُساهمةموضوع: رد: 5-HIAA   الأحد 20 يونيو - 9:49

rrrrrrrrrrrrrrrrrrrrrrrrrrr
الرجوع الى أعلى الصفحة اذهب الى الأسفل
mragab
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ذكر
عدد المساهمات : 58
العمر : 27
تاريخ التسجيل : 29/03/2011

مُساهمةموضوع: رد: 5-HIAA   الخميس 7 أبريل - 5:10

جزاكم الله خيرا على المجهود الرائع اللى انتوا بتقوموا به
الرجوع الى أعلى الصفحة اذهب الى الأسفل
reda hammoda
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ذكر
عدد المساهمات : 32
العمر : 32
تاريخ التسجيل : 09/10/2011

مُساهمةموضوع: رد: 5-HIAA   الأحد 9 أكتوبر - 1:49

مشكور
الرجوع الى أعلى الصفحة اذهب الى الأسفل
alfaez
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ذكر
عدد المساهمات : 95
العمر : 33
تاريخ التسجيل : 17/01/2013

مُساهمةموضوع: رد: 5-HIAA   الأحد 7 أبريل - 11:44

حلو
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5-HIAA
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