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Triiodothyronine (T3) is a thyroid hormone. It plays an important role in the body's control of metabolism.
A laboratory test can be done to measure the amount of T3 in your blood.
See also:
Alternative NamesTriiodothyronine; T3 radioimmunoassay
How the test is performedBlood is typically drawn from a vein, usually from the inside of the elbow or the back of the hand. The site is cleaned with germ-killing medicine (antiseptic). The health care provider wraps an elastic band around the upper arm to apply pressure to the area and make the vein swell with blood.
Next, the health care provider gently inserts a needle into the vein. The blood collects into an airtight vial or tube attached to the needle. The elastic band is removed from your arm. Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding.
In infants or young children, a sharp tool called a lancet may be used to puncture the skin and make it bleed. The blood collects into a small glass tube called a pipette, or onto a slide or test strip. A bandage may be placed over the area if there is any bleeding.
How to prepare for the testYour health care provider will instruct you, if necessary, to stop taking drugs that may interfere with the test.
Drugs that can increase T3 measurements include:
- Birth Control pills
- Clofibrate
- Estrogens
- Methadone
Drugs that can decrease T3 measurements include:
- Anabolic steroids
- Androgens
- Antithyroid drugs (for example, propylthiouracil and methimazole)
- Lithium
- Phenytoin
- Propranolol
When the needle is inserted to draw blood, some people feel moderate pain, while others feel only a prick or stinging sensation. Afterward, there may be some throbbing.
Why the test is performedThis test is done to check your thyroid function. Thyroid function is complex and depends on the action of many different hormones, including thyroid-stimulating hormone (TSH) and T4.
Sometimes it can be useful to measure both T3 and T4 when looking at thyroid function. For example, in some cases of hyperthyroidism, T3 may be increased but T4 may be normal.
The T3 test can measure both the T3 that is attached to proteins and floating free in the blood.
Your doctor may order this test if you have signs of a thyroid disorder, including:
- Hyperthyroidism
- Hypopituitarism
- Hypothyroidism - primary
- Hypothyroidism - secondary
- Thyrotoxic periodic paralysis
The range for normal values is 100 to 200 ng/dL (nanograms per deciliter).
Normal value ranges may vary slightly among different laboratories. Talk to your doctor about the meaning of your specific test results.
What abnormal results meanGreater than normal levels may indicate:
- High levels of a protein that carries T3 in the blood (may occur in pregnancy, with use of birth control pills or estrogen, liver disease, or as part of an inherited condition)
- Hyperthyroidism (for example, Graves disease)
- T3 thyrotoxicosis (rare)
- Thyroid cancer(rare)
Lower than normal levels may be due to:
- Long-term illness
- Hypothyroidism(for example, Hashimoto's disease)
- Starvation
Other conditions under which the test may be performed:
What the risks areVeins and arteries vary in size from one patient to another and from one side of the body to the other. Obtaining a blood sample from some people may be more difficult than from others.
Other risks associated with having blood drawn are slight but may include:
- Excessive bleeding
- Fainting or feeling light-headed
- Hematoma (blood accumulating under the skin)
- Infection (a slight risk any time the skin is broken)
Pregnancy and liver disease will falsely raise the T3 level. In these cases, it is useful to measure either the free T3 level or to perform the T3RUtest.
ReferencesAACE Thyroid Task Force. American Association of Clinical Endocrinologists medical guidelines for clinical practice for the evaluation and treatment of hyperthyroidism and hypothyroidism. Endocr Pract. 2002;8(6):457-469.
Ladenson P, Kim M. Thyroid. In: Goldman L and Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders; 2007:chap 244.
What else can I help you with?
What is the normal lab value for free t3?
According to the test results from the hospital normal values are between 3.1-6.8 pmol/L
Does T3 and T4 increase the rate of oxygen consumption?
Yes, both T3 and T4 thyroid hormones play a role in increasing the rate of oxygen consumption in the body by stimulating cellular metabolism. T3 is the more biologically active form, but T4 can also be converted to T3 in tissues to exert similar effects on metabolic rate.
What color tube is used for t3 uptake?
A red-stoppered tube is typically used to collect blood for T3 uptake testing. It contains no additives, allowing the blood to clot before analysis.
Are hormones t3 and t4 water soluble?
No, T3 and T4 are not water soluble. They are lipophilic hormones, meaning they are soluble in lipids (fats) but not in water. This affects how they are transported in the bloodstream and how they interact with cells in the body.
What color tube is a t3 t4 drawn in?
It is called serum-separator-tube (SST) and it is dark yellow (just so there's no confusion there are two yellow tops when it comes to blood draws and the orders each go in and that is light yellow and dark yellow).
Is free T3 a fasting test?
no
What is a free T3 test?
T3 is a thyroid hormone. Hormones occur in two different states in the body-bound (to a protein) and free (not bound to protein). A free T3 test is one that measures the concentration of unbound T3 in the blood.
How do you check t3?
this is a test for your thyroid and its done with a blood draw
Could you use the canon rebel t3 for youtube videos?
You can use the Canon Rebel T3 Video Test for YouTube videos.
What is the significance of a high T3 thyroid blood test mean?
According to the American Thyroid Association, T3 (Triiodothyronine) tests are useful in diagnosing hyperthyroidism and the severity of it. This is because patients who are hyperthyroid have an elevated T3 level.
What tests are needed to diagnose hypothyroidism besides tsh?
In addition to the test for TSH, the value of which is questioned by some, T3, T4, and Free T3 and Free T4 are often used to help diagnose hypothyroidism. A Reverse T3/Free T3 Ratio is also used by some doctors.
Will t3's effrigen tablets show up on a drugs test?
Yea they will, I failed myn.
In thyroid what is t3 t4 test what is the best way to track hypo thyroid?
T3 is triiodothyronine, and is the active form of the hormone secreted by the thyroid. T4 (thyroxine) is another form of thyroid hormone which must be converted to T3 by your body via the deiodinase enzyme. Although T3 is active, your body produces much more T4. The best way to monitor low thyroid function is by looking at TSH (thyroid stimulating hormone). TSH will be high if the thyroid is not producing enough T3/T4. For the majority of hypothyroid cases, only TSH needs to be monitored. For hyperthyroidism and some hard to treat hypothyroid cases, the doctor will test T3 and T4.
Why are they reluctant to do the thyroid T4 test?
The old Total T4 test (TT4) is no longer considered the best way to test for T4 levels. T4 and T3 can both be bound by other proteins and hormones in the body. When this happens, the T4 or T3 is not usable by the body. The body can only use T4 and T3 that is not bound, or free. For this reason, Free T4, which only tests the free levels of the hormone, is now preferred over Total T4 testing as more accurate.
Does E1 offer the fastest communication speed?
I know Murray is making this test hard! lol. anyway. its T3
What medications must be stopped before a T3 test?
Steroids, propranolol (Inderal), cholestyramine (Questran), and other medications that may influence thyroid activity are usually stopped before a triiodothyronine (T3) test.
How do they check a dogs thyroid?
The Veterinarian will check a dog's thyroid with blood work, such as a T3, T4 and a TSH test.
