clinical definition of total t3 (total triiodothyronine)
The thyroid is a butterfly-shaped, small gland present in the neck region and is responsible for various functions of the body including metabolism and growth. Triiodothyronine(T3) is one of the hormones produced by the thyroid gland. This test is conducted to evaluate thyroid functioning and measures the blood level of the hormone T3. T3 is four times more potent than T4. Being secreted by the thyroid gland, T3 and T4 function a major role in the growth of the human body.
The Total T3 test measures both the bound and free forms of T3 in blood. T3 exists in two forms - the more abundant form, which is attached to proteins that facilitate transporting of the hormone through the body and the less abundant form called T3 which circulates unattached.
what is total t3 test?
The Total T3 test measures the bound(T3) and free forms of T3(FreeT3) levels in the blood to evaluate the thyroid functioning if it has underactive(Hypothyroidism) or overactive(Hyperthyroidism) performance.
why do i need this test?
Total Triiodothyronine is conducted to check for thyroid dysfunction. It helps in diagnosing hyperthyroidism, a condition wherein the thyroid overproduces hormones. This test helps to detect infertility in females. This test is not affected by the protein level and thus is more accurate. A hyperactive thyroid (overactive thyroid gland function), hypoactive thyroid(low thyroid gland function) and hypopituitarism(under-active pituitary gland) are some of the disorders that affect the thyroid gland.
what other tests might i have along with this test?
TSH and T4 are other tests taken along with T3 tests for accurate interpretation of the thyroid gland functioning. The pituitary gland that produces TSH(Thyroid stimulating hormone), stimulates the release of T3 and T4 by the thyroid gland. Taking all three test namely TSH, T3 andT4 helps to understand the working of the thyroid gland better. Also, the test is taken later part of the treatment again to know whether the working of thyroid gland shows improvement.
what do my test results mean?
Pregnancy affects T3 test levels. High T3 level indicates Hyperthyroidism or thyroiditis or goitre. It is also caused by too much of iodine in blood/ too much protein /germ cell tumours/ too much thyroid medication. Abnormally low-level T3 indicates hypothyroidism, iodine deficiency, dietary issues like fasting and pituitary problems. High t3 symptoms might also be due to liver disorder. 'Euthyroid sick syndrome' also recognized as Low T3 syndrome, is known by the increase in TSH and/no increase in reverse T3 (rT3), decreased thyroxin T4 levels and/or serum T3.
what are the reasons to take the total t3 test?
Insufficient amounts of T3, show symptoms associated with hypothyroidism and a slowed metabolism, like:
• Weight gain
• Dry skin
Excessive amounts of T3 in the blood results in symptoms associated with hyperthyroidism, like:
• Weight loss
• Faster heart rate
• Puffiness around dry, irritated eyes
• Trembling and sweating
how is this test done?
This test is a blood test where a sample is collected by inserting a needle through your vein in the arm. A vein from the arm is selected. A large rubber strap is used to tighten the vein site. The skin over the vein is cleaned with an alcohol swab to insert the needle. Blood will be collected into one or more tubes, and the strap will be removed. A cotton piece is given to stop the blood.
does this test pose any risk?
Some risks may come with this test as infections are known to occur with the use of needles. You may experience bleeding, bruising, or a hint of pain. The site where you are injected may feel sore for a while once the blood sample is collected. Use a cotton pad to stop the blood, if any. Otherwise, there are no specific risks involved in a T3 blood test.
what might affect my test results?
The only variables which may affect your test results are your nutritional diet, lifestyle and any other existing medications you're currently on. Please inform your doctor if you're using any medications before you take this test.
Specimen type: Serum(Blood Sample), Specimen collection procedure: Venipuncture(Collection of blood from a vein, usually from the arm)
how do you understand this result?
In both male and female, the FreeT3 normal range is 230-619 pg/dl, and TT4 normal range is 70-204 ng/dl.
how do i prepare for the test?
• No Fasting Required.
• No other special preparations required.
No special preparations are required for preparing for this test. The pills that you take affects the Ft3 blood test to an extent. So it is always advisable to inform your doctor if you are currently on any medication. The doctor might ask you to temporarily stop taking the pills to get the accurate results in the FT3 blood test. The medications that impact the test results are steroids, thyroid tablets like Thyronorm or Eltroxin, birth control pills and cancer-treating drugs. Inform the doctor if you take any of them and or any herbal treatment as well.
what is the test cost?
The T3 T4 TSH test cost ranges between 300 to 500 rupees depending on the city.
Understanding results ofTotal T3 (Total Triiodothyronine)
|16 yrs Children||115-219 Boy(ng/dL), 107-199 Girl(ng/dL)|
|18-19 yrs Children||79-152 Boy(ng/dL), 52-139 Girl(ng/dL)|
|15 yrs Children||112-224 Boy(ng/dL), 105-198 Girl(ng/dL)|
|9-10yrs Children||141-220 Boy(ng/dL), 132-255 Girl(ng/dL)|
|13 yrs Children||134-262 Boy(ng/dL), 132-239 Girl(ng/dL)|
|12 yrs Children||139-235 Boy(ng/dL), 146-219 Girl(ng/dL)|
|17 yrs Children||76-164 Boy(ng/dL), 78-188 Girl(ng/dL)|
|Male||70 to 204 ng/dL|
|Female||70 to 204 ng/dL|
|8-15 days Children||98-377 Boy(ng/dL), 83-372 Girl(ng/dL)|
|1-7 days Children||210-578 Boy(ng/dL), 238-534 Girl(ng/dL)|
|4-6 yrs Children||112-236 Boy(ng/dL), 148-261 Girl(ng/dL)|
|1-3 yrs Children||126- 253 Boy(ng/dL), 138-217 Girl(ng/dL)|
|7-8 yrs Children||125-260 Boy(ng/dL), 143-270 Girl(ng/dL)|
|9-10yrs Children||114-213 Boy(ng/dL), 109-202 Girl(ng/dL)|
|14 yrs Children||128-220 Boy(ng/dL), 117-213 Girl(ng/dL)|
“* Reference ranges may vary between labs depending on instruments used and method of establishment of reference ranges’’
T3 total tests help doctor conclude on the thyroid gland functioning and advice you on proper dosage to keep the T3, T4 and TSH within the normal range.