t3 test

T3 Test: What To Expect, Need, Procedure ,Cost, Recovery

Your doctor suggests a T3 test to determine thyroid problems. It is useful in detecting the severity of thyroid disorders like hyperthyroidism. Patients suffering from hyperthyroidism tend to show elevated levels of T3. It is also known as triiodothyronine. Your thyroid gland produces thyroid hormones like triiodothyronine and thyroxine (T4) to regulate several functions in your body. Triiodothyronine and T4 together are known as thyroid hormones. It regulates your metabolism, body temperature, and heart rate. The organ located in your neck has significant functions. So, any disorder that causes its abnormal function needs immediate attention.

T3 test

Functions Of Thyroid Gland

Functions Of Thyroid Gland

Before getting into the details of the triiodothyronine test, you need to understand about the thyroid gland. The thyroid gland is a small yet vital gland in your body. It weighs less than an ounce and has a butterfly shape. The gland is located in front of your neck. It has two lobes, which lie along the trachea or windpipe. A narrow band of tissue (isthmus) joins the two lobes of the gland. It lies below the larynx (Adam’s apple). The thyroid glands form inside a human body during the development of the fetus. It normal originates in the back of the tongue. But, it transfers to the front of the neck before birth. In some cases, it fails to migrate properly. So, it ends up in the backs of the tongue (lingual thyroid), too far in the chest or high in the neck. Such conditions occur rarely.

How Does It Work?

The main function of the thyroid gland is to take iodine from the different foods you consume. It gets converted into T4and triiodothyronine (T3). Your thyroid cells are the only cells in the human body capable of absorbing iodine. The thyroid cells combine amino acid tyrosine and iodine to make T3 and T4. Your thyroid gland releases them into the bloodstream. It is transported throughout the body to control your metabolism. So, these hormones play an important role in converting calories and oxygen to energy. Every cell in your body depends on the thyroid hormones for metabolism regulation. In normal cases, a healthy thyroid gland produces 80% of T4 and 20% of triiodothyronine. It is because triiodothyronine has four times more hormonal strength compared to T4.

Thyroid Gland T3 Works

The pituitary gland controls your thyroid gland. When your triiodothyronine or T4 levels drop too low, the pituitary gland produces Thyroid Stimulating Hormone (TSH). It stimulates your thyroid gland to produce more hormones. Your thyroid gland under the influence of TSH manufacturers and secretes T3 and T4. So, its levels increase in your body.

About T3

Triiodothyronine is produced by your thyroid gland and by other tissue through de-ionization. De-ionization refers to the enzymatic conversation of T4 by other tissues. The hormone is responsible for the following:

  • Maintenance of bone health
  • Brain development and function
  • Muscle control
  • Heart function
  • Metabolic rate
  • Digestive functions

In normal cases, T3 or triiodothyronine in the human body binds to protein. The triiodothyronine that does not bond to protein is known as free T3. It circulated unbound in your bloodstream. Your doctor orders the common T3 total test to measure triiodothyronine and free triiodothyronine.

Need For T3 Test

The doctor suggests a triiodothyronine test to detect the hormone levels in your body. It is usually suggested to detect any problem with the thyroid gland. So, if your doctor suspects any potential thyroid disorders, then you need to undergo the test. The test can detect the following problems:


It is the condition triggering excess thyroid hormone production. It can cause changes in your body and affects its normal function.


The test also detects the malfunctioning of your pituitary gland. In some cases, your pituitary gland may not produce normal levels of pituitary hormones. So, the test can detect such problems.

Primary/Secondary Hypothyroidism

If your doctor suspects primary or secondary hypothyroidism, then you need to undergo the test. Primary hypothyroidism refers to the disease in the thyroid glands that causes high levels of TSH (Thyroid Stimulating Hormones). Secondary hypothyroidism develops when your pituitary or hypothalamus suffers any problem. It can cause your TSH levels to go down.

Thyrotoxic Periodic Paralysis

It is a condition developing due to the production of high levels of thyroid hormones. The abnormal levels of thyroid hormones can result in muscle weakness.

When To See A Doctor?

When you suffer from a thyroid disorder, it can trigger a wide range of symptoms. So, you need to monitor your body for signs. When you see the following signs, make an appointment with the doctor to confirm the thyroid disorders:

Mental Problems

Imbalance of thyroid hormones can affect mental health. So, people experiencing a drastic fluctuation of the hormones can see several mental issues like:

  • Cognitive dysfunction
  • Psychosis
  • Affective disorders

Physical Problem

The fluctuations in thyroid hormone can slow your metabolism. The lack of thyroid hormone can trigger issues like:

  • Menstrual irregularity in women
  • Constipation
  • Fatigue
  • Weakness
  • Trouble sleeping
  • Increased sensitivity to cold or heat
  • Difficulty sleeping
  • Weight gain or weight loss
  • Puffy or dry skin
  • Bulging, irritated, puffy or dry eyes
  • Hand tremors
  • Hair loss
  • Increased heart rate

If you already take medications for your thyroid problem, then the test can detect any changes in your condition. It is useful in determining the correct dose of medication you need to take to manage the hormonal fluctuation. Your doctor orders T4 or TSH along with the T3 test to determine your exact condition. Detecting the Thyroid Stimulating Hormone (TSH) and T4 can give a complete picture of your health condition and take action accordingly.

Preparing For T3 test

You need no special preparation for the test. So, you never have to skip food or drinks to undergo the test. On the day of the test, you need to visit the hospital or lab to give your blood. Acute illness can interfere with the test results. So, your doctor avoids testing of hormones in hospitalized patients. It is usually deferred until the patient has recovered from the illness.

Inform About Illness/Medications

Before the procedure, you need to inform your doctor about the medication you take and any disease you suffer. Certain conditions like pregnancy or liver disease affect the triiodothyronine test results. It is also important to give information about the medication you take in advance. In such cases, your doctor can advise you to stop taking the medication for a short period or consider their effect on the results while interpreting it. The medication that affects T3 test results are:

  • Steroids
  • Thyroid-related medications
  • Hormonal drugs containing estrogens or androgens (like birth control pills)

While visiting the hospital or lab to give your blood sample, you need to wear comfortable clothing. It is preferable to wear a short-sleeved dress. It makes it easier for the phlebotomist to find a vein and draw blood. Loose clothing is ideal while giving your blood sample.

The Procedure For T3 Test

During the procedure, your phlebotomist cleans the surface on your upper arm. It is the first area to check for a vein to draw blood. After finding the vein, the technician uses an antiseptic wipe to clean the area surrounding the vein. An elastic band is (also known as a tourniquet) placed around the upper arm to apply pressure. This step causes your veins to swell with blood. The health professional inserts a needle into the vein. Usually, the health professionals take the blood from a vein in the arm inside of the elbow. If the vein is not available to draw blood, then they choose veins on the back of the hand for collecting a blood sample. The technician collects the blood in a vial or syringe.

After the procedure, the technician removes the elastic band. Once the phlebotomist collects blood, they remove the needle from your vein and cover the area with cotton or bandage. The phlebotomist places cotton with pressure to encourage blood clotting. You can remove the cotton or bandage after some time. The whole process takes only a couple of minutes.

What To Expect After T3 Test

Withdrawing blood from any of the regions (your vein in the area between the elbow and upper arm or hand) can make you feel uncomfortable. Pricking of the needle for drawing can cause pain for a short time. You can also see mild bruising. It will go on its own without any treatment after a few days. These are normal occurrences and you have no reason to panic.

Getting the Results

In normal cases, a machine processes the blood sample. You receive the results after a few hours after the test or the next day. The normal results range from 100 ng/dL to 200 ng/dL (nanograms per deciliter)

A normal result does not indicate proper thyroid functioning. So, your doctor measures T4 as well as TSH to figure out your exact problem. You can suffer from a thyroid problem even with a normal T3 result.

Meaning Of Abnormal T3 Test Results

A thyroid test is complicated. So, one test alone may not offer a definitive insight into your problem. The doctor tends to suggest multiple tests to detect the actual problem. But, an abnormal test result can give an idea of the problem you suffer. To make a proper diagnosis, your doctor chooses to perform a TSH or T4 test to gain a clear picture of the thyroid function. Abnormal triiodothyronine result is common among women who are pregnant or who suffer from liver disease. So, your doctor orders for free T3 level testing to rule out pregnancy and liver disease as the root cause of abnormal results. The abnormal test results can mean the following:

High T3 levels

Elevate levels of the triiodothyronine result can indicate different thyroid issues. So, people suffering from the following can have high triiodothyronine results:

Graves’ disease

If you suffer from the autoimmune disorder, then you have an abnormal triiodothyronine level. So, it can mean you suffer from overactive thyroid or hyperthyroidism. When you suffer from the autoimmune problem, your immune system attacks the thyroid system. So, it results in your body making more thyroid hormones than normal body requirements.


Abnormal triiodothyronine levels indicated an overactive thyroid. So, it triggers your thyroid gland to produce more thyroxine hormone. Your doctor refers to the condition as hyperthyroidism. It can accelerate your body’s metabolism. So, you can suffer from the irregular or rapid heartbeat. Hypothyroidism can also result in unintentional weight loss.

Painless Thyroiditis

The condition also known as silent thyroiditis is an immune reaction of the thyroid gland. The disorder first causes hyperthyroidism. Then, you suffer from hypothyroidism.

Thyrotoxic Periodic Paralysis

Thyrotoxic Periodic Paralysis

High levels of thyroid hormone in the blood can trigger severe symptoms. Thyrotoxic periodic paralysis is one such condition. It can trigger episodes of severe muscle weakness. It is a rare condition that affects Hispanic and Asian men.

Toxic Nodular Goiter

People who develop goiter can suffer from the condition when they fail to get treatment for the condition. Toxic nodular goiter arises due to long-standing goiter. When you suffer from the condition your thyroid glands becomes enlarged. The nodules (small rounded mass/masses) starts to produce too much thyroid hormone. Old people, especially women above 55 are prone to develop health problems.

High levels of Triiodothyronine in your tests can also point toward high levels of protein in your blood. In some rare cases, the elevated levels of triiodothyronine indicate thyrotoxicosis or thyroid cancer.

Low T3 Levels

Abnormally low levels of Triiodothyronine hormones can indicate your poor health. It mostly points towards starvation or hypothyroidism. It also points towards a long-term illness as these hormone levels decrease when you fall sick. When your health is poor and you need hospitalization, your T3 hormone levels go lower.

Triiodothyronine tests alone cannot offer better insight into the disease troubling your health. Various factors can cause levels to decrease. So, your doctor often suggested T4 and TSH tests along with the Triiodothyronine test to gain a good perspective about the thyroid gland working. The combination of all these hormone tests can only offer a complete picture.

Risks Of T3 test

The T3 test is simple and has no serious risks associated with it. You feel slight discomfort during the drawing of blood. While it is a safe procedure, you can expect minor problems due to drawing of blood like:

  • Bruising at the puncture site (where the technician draws blood)
  • Minor bleeding
  • Light-headedness

The risks are not severe. So, you will get better within a few minutes. So, it needs no special treatment or care. But, some people (in rare cases) can suffer from severe risks associated with withdrawing blood. Therefore, you need to monitor the following signs:

Excessive Bleeding

People who suffer from blood disorders have a decreased ability of blood clotting. In such cases, they can suffer from excessive bleeding after drawing blood. Patients taking blood thinner medication like aspirin can also experience the problem. So, informing beforehand about the condition can prevent such occurrences.

Inflammation of the vein

The needles used to draw blood cause minimal damage to the vein due to its special design. But, in some cases, repeated blood tests can cause vein inflammation or scarring. Repeated use of vein for drawing blood can cause vein damage. The number of times varied from one person to another. You cannot draw blood from a damaged vein. It is a rare problem.



It is the condition occurring due to the blood accumulating under your skin after the phlebotomist draws blood. The accumulated blood can lead to the formation of a bruise or lump.


Some people may have no visible veins. So, the phlebotomist punctures multiple sites to locate a vein and draw blood. The problem also occurs when an inexperienced phlebotomist draws the blood. Multiple punctures can trigger pain and discomfort. Therefore, you need to inform in advance about the difficulty to find the vein for drawing blood.

Fear Of Needles

Fear of needles or needle phobia can affect most of the children and a small number of adults. In such cases, the affected person has an extreme fear of procedures involving hypodermic needles or injections. Such people tend to fear for relatively painless procedures like drawing blood. Due to their anxiety and stress, they tend to experience the following signs:

In such cases, it is important to explain the test and make them feel comfortable. For kids, parents need to stay while drawing blood. Making the child understand the procedure can ease some of the fear and anxiety. As tensing muscles can only make it difficult and painful to draw blood, the person needs to relax. So, distracting from looking into the procedure can help.

Cost Of T3 Test

The cost of the T3 test can range from $10-$15. In India, the cost of the test is relatively low. You can undergo the test by just paying INR 300 to INR 500.


Triiodothyronine (T3) and Thyroxine (T4) hormones are important for the proper functioning of your body. It is produced by the thyroid gland. The hormones play an important role in the physical development or infant and small kids. While these hormones are essential for metabolic activity in adults. You need these two thyroid hormones to help the function of vital organs properly. So, your body needs the right balance of triiodothyronine and thyroxine for the brain, heart, muscles, liver, and other organs to function properly. Unregulated thyroid imbalances can cause life-threatening complications. Dangerously low or high triiodothyronine can trigger severe complications. So, you need to monitor the hormones to prevent health properly. By undergoing the hormone test you can detect any problem and take action immediately. It improves the outcome and ensures a good quality of life.

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