FT3 (Free Triiodothyronine 3)

What is the FT3 (Free Triiodothyronine 3) Test?

T3 sometimes referred to as triiodothyronine, is a crucial thyroid hormone that controls metabolism and makes sure your body can carry out critical processes effectively. While the majority of T3 in the circulation is protein-bound, part of it is unbound or free. In contrast to the total T3 test, which examines both bound and free T3, the free T3 test assesses the active form of T3 that is not bound to protein. If a thyroid condition is suspected, a free T3 or total T3 blood test may be requested to assess thyroid function. Moreover, they can be used to diagnose thyroid illness severity and type, monitor thyroid condition therapy, and examine pituitary gland issues. 

Your thyroid is a tiny, butterfly-shaped gland that is covered by the skin at the front of your neck. Your endocrine system contains (Controls/regulates) it. One of the two primary thyroid hormones is triiodothyronine (T3). The other hormone is thyroxine or T4. Blood tests are used by healthcare practitioners to measure T3 levels. There are two types of triiodothyronine: 
 

• Free T3: This form reaches the tissues of your body where it is required. 
• Bound T3: This form binds to proteins and keeps them out of the tissues of your body.

 
What is the purpose of the FT3 (Free Triiodothyronine 3) Test? 

Testing for free T3 is used to assess thyroid function. The diagnosis of thyroid disorders, such as an overactive or underactive thyroid gland, determining the severity of thyroid issues, identifying disorders of the pituitary gland, and monitoring patients with known thyroid conditions all involve free T3 tests in addition to other thyroid function tests. If you've had a thyroid-stimulating hormone (TSH) test that was abnormal, T3 testing could be utilized as a follow-up test. A thyroid panel, a collection of tests used to assess thyroid function, frequently includes a free T3 test. 

What does the FT3 (Free Triiodothyronine 3) Test diagnose?

T3 is a thyroid hormone with significant physiological effects. T3 controls the body's metabolism, stimulates cells, and permits the function of essential organs with T4, another crucial thyroid hormone. Because triiodothyronine contains three iodine atoms connected to it, this hormone is known as T3. Thyroxine, often known as T4, the second most common thyroid hormone, contains four iodine atoms. The thyroid produces some of the T3 that is present in your bloodstream. Nevertheless, the majority of it begins as T4 and then undergoes iodine atom removal in the blood to change into T3. 

Around 80% of the T3 in your blood is produced by your body's outside-of-the-thyroid-gland conversion of T4 to T3. Whereas the free T3 test only evaluates the T3 that is not bound to protein, the total T3 test measures both bound and free T3. T3 readings are frequently combined with other thyroid function tests, such as TSH, free, and total T4 levels, to assess your thyroid's health.

Why do you need an FT3 (Free Triiodothyronine 3) Test?

When your doctor thinks you may have a thyroid condition, you will often have a free or total T3 test. This could be the case if you received an abnormal TSH test result or if you are exhibiting hyperthyroidism symptoms, which include: 
 

• Changes in weight, generally a loss of weight 
• Fatigue 
• Often passing the poop 
• Hair fall 
• Higher appetite 
• Increased perspiration 
• Irregular menstrual periods 
• Heart flutters 
• Insomnia 
• Anxiety or jitters 
• Low concentrations 
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T3, despite its potential value, is less useful in the diagnosis of hypothyroidism since it is frequently the last hormone to develop aberrant in a hypothyroid person. 

Preparation and procedure required for FT3 (Free Triiodothyronine 3) Test 

Typically, a total or free T3 test is requested by a clinician as part of a panel or collection of thyroid tests. Common places for testing include a doctor's office, hospital, clinic, or medical laboratory. Never stop taking any medicine without first consulting your doctor. Your free or total T3 test results may be impacted by a variety of drugs. They comprise: 
 

• Pills for birth control 
• Estrogen and other female hormones methadone 
• Some dietary additives or herbs 
• Steroids 
• Androgens (male hormones) 
• Lithium 
• Propranolol 
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A vein in your arm is most frequently used to draw blood. Your upper arm may be bound by a band as the sampler cleans a tiny area of skin on your arm. They will then place a needle with a collecting tube connected to the cleaned region and extract a little amount of blood. Blood sampling usually takes no longer than three minutes. You will be instructed to gently press on the area with a bandage or piece of gauze after your blood sample has been obtained and the needle has been withdrawn. By doing so, you can halt the bleeding and possibly avoid bruises. The bandage will then be put on. After the exam, you can get back to your regular activities. 

Understanding of the FT3 (Free Triiodothyronine 3) Test results 

Interpretation: 

There may be a little difference across laboratories in the normal value ranges for any lab test, including T3 (triiodothyronine) testing. Verify your results against the reference range listed in your lab report. Your healthcare practitioner will clear your queries regarding your results. A blood draw has a little amount of risk attached. In the location where the sample was taken, you could experience a little bruising. 

Normal amounts of free T3 

Although it is feasible to test these levels, providers often do not order free T3 tests since they are not as accurate. (THIS STATEMENT IS NOT REQUIRED )The following are typical free T3 levels for healthy individuals:
 

• Picograms per millilitre (pg/ml) range from 1.4 to 5.4 in infants under 3 days old. 
• 4 to 30-day-old infants: 2.0 to 5.2 pg/ml 
• Infants aged one month to one year: 1.5–6.4 pg/ml 
• Children aged 1 to 6: 2.0–6.0 pg/ml 
• Children aged 7 to 11: 2.7 to 5.2 pg/ml 
• Children of age 12 to 17: 2.3–5.0 pg/ml 
• Adults of age 18 to 99: 2.3–4.1 pg/ml 
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Often, higher-than-normal T3 levels signify hyperthyroidism (overactive thyroid). 
 

• Loss of weight without cause. 
• feeling uneasy or anxious. 
• more frequent bowel motions. 
• irregular or fast pulse (arrhythmia). 
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Your T3 levels may be below normal if you have hypothyroidism (underactive thyroid). T3 testing is frequently the last of the thyroid function tests to provide aberrant results, therefore healthcare professionals don't normally depend on it to identify hypothyroidism.