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What Is The Blood Test For Thyroid Levels

What Do The Results Mean

TSH test explained | Thyroid stimulating hormone test | Thyroid function test | Blood TSH test

High TSH levels can mean your thyroid is not making enough thyroid hormones, a condition called hypothyroidism. Low TSH levels can mean your thyroid is making too much of the hormones, a condition called hyperthyroidism. A TSH test does not explain why TSH levels are too high or too low. If your test results are abnormal, your health care provider will probably order additional tests to determine the cause of your thyroid problem. These tests may include:

  • T4 thyroid hormone tests

Learn more about laboratory tests, reference ranges, and understanding results.

Are There Any Specific Tests For Hypothyroidism

Thyroxine is the primary hormone produced by the thyroid gland in response to stimulation by the pituitary gland.

A âfeedback systemâ exists between the thyroid gland and the pituitary gland. When T4 concentrations in the blood are low, the pituitary sends a signal to the thyroid gland using thyroid stimulating hormone , prompting the thyroid gland to produce more T4. When T4 levels in the circulation are adequate, the pituitary decreases its production of TSH, thereby reducing the production of T4.

âIf the total T4 concentration is well within the normal range, then your dog is not hypothyroid.â

Total T4 . ;T4 circulates in the blood in two forms; one form of the hormone is bound, or attached to proteins in the blood, while the other form circulates freely within the blood stream. Total T4 measures both forms of the hormone in a blood sample. If the total T4 concentration is well within the normal range, then your dog is not hypothyroid. If the total T4 concentration is at the low end or below the normal range, and your dog has supportive clinical signs, then hypothyroidism is likely. Unfortunately, there are conditions other than hypothyroidism that may cause the total T4 value to be reduced. These conditions include the presence of another illness or the administration of some drugs, such as anti-inflammatory medications. Your veterinarian may be able to measure total T4 levels in the veterinary office.

Side Effects And Aftercare

A blood draw is a routine, minimally invasive procedure. During the days immediately after the blood draw, you may notice slight bruising or soreness at the area where the needle was inserted. An ice pack or an over-the-counter pain reliever can help ease your discomfort.

If you experience a great deal of pain, or if the area around the puncture becomes red and swollen, follow up with your doctor immediately. These could be signs of an infection.

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How Long Does It Stay In Your System

Synthroid stays in your body for about 6 to 7 days after youve taken a dose

However, you should try to keep thyroid hormone levels consistent in your body while youre taking Synthroid. To do this, its important to take the drug as your doctor directs, and to not skip doses.

Using more than the recommended dosage of Synthroid can lead to serious side effects. Do not use more Synthroid than your doctor recommends.

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Thyroxine Triiodothyronine And Tsh Levels

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The main job of the thyroid gland is to make the hormone thyroxine, also known as T4 because it has four iodine molecules. The thyroid also makes the hormone triiodothyronine, known as T3 because it has three iodine molecules, but in smaller amounts, explains Cathy Doria-Medina, MD, an endocrinologist with HealthCare Partners Medical Group in Torrance, California. The thyroid gland makes mostly T4, the T4 has to be converted to T3, because T3 is the part of thyroxine that actually does the work, she says.

The pituitary gland at the base of the brain controls hormone production in your body. It makes thyroid-stimulating hormone , which tells the thyroid gland how much T4 and T3 to produce. The TSH level in your blood reveals how much T4 your pituitary gland is asking your thyroid gland to make. If your TSH levels are abnormally high, it could mean you have an underactive thyroid, or hypothyroidism. Thats because it indicates your pituitary gland is producing more TSH in an effort to stimulate your thyroid to produce thyroid hormone, according to the Mayo Clinic.

TSH levels go in the opposite direction of your thyroid hormone, Dr. Doria-Medina explains. If youre making too little thyroid hormone, your TSH will go up. If youre making too much thyroid hormone, your TSH will go down.

If your TSH is higher than 4.0 mU/L on repeat tests, you probably have hypothyroidism.

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How Do I Prepare For The Test

This blood test may be done any time during the day. Certain medicines can affect the results of your thyroid test. Ask your healthcare provider if you should wait to take your medicines until after your blood is taken. Wear a short-sleeved or loose shirt on the day of the test. This will make it easier to draw your blood.

Are Normal Values The Same For Everyone

No. Whats normal for you might not be normal for the person next to you.

Whats normal for you today will likely not be normal for you in the future.

Your weight, stress levels, or dietary habits might change you might get pregnant, move countries, and more. These variables and your genes will determine your normal values for any given moment in your life.

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Thyroid Hormone Level Tests

There are four main thyroid hormones that have been identified: T1, T2, T3 and T4.

T4 and T3 are the two main thyroid hormones. T4 is known as prohormone and is 300 percent less biologically active than T3. T3 is the main biologically active thyroid hormone and gives us beautiful hair, replenishes our energy, and runs our metabolism.

You may have put together that most of the commonly prescribed thyroid medications like Synthroid and levothyroxine, only contain T4 , and thus they need to be converted to the active T3 form in the body.

On paper, the T4 to T3 conversion happens just fine, but in the real world, in real human bodies, we may not always convert T4 to T3.

We can reveal our T4 to T3 ratios and measure the hormone that is available to do its job in the body, by testing our free T4 and free T3 levels.

Free T3 and Free T4 tests measure the levels of active thyroid hormone circulating in the body.

Some clinicians may only test for T4, but T3 is also important to test, as some individuals may not be converting T4 to the active T3 properly. Thus, people may have a normal T4, but a low T3 level.

How Do You Know If You Are Converting Correctly?

Take a look at your free T3 and free T4 levels. Both should be in the optimal range. If the T4 is optimal, but the T3 is out of the optimal range, you know that your body is not making enough T3 hormone from the T4.

Optimal T4 reference range: 15-23 pmol/L

Optimal T3 reference range: 5-7 pmol/L

Radioactive Iodine Uptake Test

Thyroid Test | Normal Thyroid Levels | Optimal Thyroid Levels | T3 vs T4

A radioactive iodine uptake test, also called a thyroid uptake test, can help check thyroid function and find the cause of hyperthyroidism. The thyroid takes up iodine from the blood to make thyroid hormones, which is why this is called an uptake test. Your health care professional may ask you to avoid foods high in iodine, such as kelp, or medicines containing iodine for a week before the test.

For this test, you will swallow a small amount of radioactive iodine in liquid or capsule form. During the test, you will sit in a chair while a technician places a device called a gamma probe in front of your neck, near your thyroid gland. The probe measures how much radioactive iodine your thyroid takes up from your blood. Measurements are often taken 4 to 6 hours after you swallow the radioactive iodine and again at 24 hours. The test takes only a few minutes.

If your thyroid collects a large amount of radioactive iodine, you may have Graves disease, or one or more nodules that make too much thyroid hormone. You may have this test at the same time as a thyroid scan.

Even though the test uses a small amount of radiation and is thought to be safe, you should not have this test if you are pregnant or breastfeeding.

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What Is Being Tested

Thyroid autoantibodies are antibodies that develop when a persons immune system mistakenly targets components of the thyroid gland or thyroid proteins, leading to chronic inflammation of the thyroid , tissue damage, and/or disruption of thyroid function. Laboratory tests detect the presence and measure the quantity of specific thyroid autoantibodies in the blood.

The thyroid is a small, butterfly-shaped gland that

Thyroid autoantibodies are antibodies that develop when a persons immune system mistakenly targets components of the thyroid gland or thyroid proteins, leading to chronic inflammation of the thyroid , tissue damage, and/or disruption of thyroid function. Laboratory tests detect the presence and measure the quantity of specific thyroid autoantibodies in the blood.

The thyroid is a small, butterfly-shaped gland that lies flat against the windpipe in the throat. The primary hormones that it produces, thyroxine and triiodothyronine , are vital in helping to regulate the rate at which the body uses energy . The body uses a feedback system;in which thyroid stimulating hormone stimulates the thyroid to produce T4 and T3 as needed. This system helps maintain a relatively stable amount of the thyroid hormones in the blood. When thyroid antibodies interfere with this process, they can lead to chronic conditions and autoimmune disorders associated with hypothyroidism or hyperthyroidism, such as Graves disease or Hashimoto thyroiditis.

Thyroid antibody tests include:

How Do I Prepare For A Thyroid

The TSH test doesnt require any special preparation. However, its important to tell your doctor if youre taking medications that might interfere with the accuracy of the TSH measurement. Some medications that could interfere with a TSH test are:

  • amiodarone
  • potassium iodide
  • biotin

You may need to avoid using these drugs before the test. However, dont stop taking your medications unless your doctor tells you to do so.

A TSH test involves taking a sample of blood. The blood is typically drawn from a vein thats inside the inner elbow.

A healthcare provider will perform the following procedure:

  • First, theyll clean the area with an antiseptic or other sterilizing solution.
  • Theyll then tie an elastic band around your arm to make the veins swell with blood.
  • Once they find a vein, theyll insert a needle into the vein to draw blood. The blood will be collected in a small tube or vial attached to the needle.
  • After they draw enough blood, theyll remove the needle and cover the puncture site with a bandage to stop any bleeding.
  • The entire procedure should only take a few minutes to complete. The blood sample will be sent to a lab for analysis.

    Once your doctor receives the test results, theyll schedule an appointment with you to discuss the results and explain what they may mean.

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    When Should I Take My Kid For The Thyroglobulin Test

    If you observe thyroid dysfunction signs and symptoms in your kids, the thyroglobulin test is highly recommended. Some of the common symptoms noticed in kids having thyroid dysfunction are:; Yellowing of the skin and whites of the eyes . In most cases, this occurs when a babys liver cant metabolize a substance called bilirubin, which normally forms when the body recycles old or damaged red blood cells.;

    What Are Thyroid Blood Tests

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    Doctors use blood tests to check for thyroid or pituitary problems. In kids already diagnosed with thyroid or pituitary problems, the tests are used to guide treatment.

    Commonly ordered thyroid blood tests include:

    • T4 test: This is done to measure the blood level of the hormone T4 . It might be done in one or both of the following ways:
    • total T4, which measures the entire amount of thyroxine in the blood, including the amount attached to blood proteins that help carry the hormone through the bloodstream
    • free T4, which measures only the thyroxine that’s not attached to proteins. This is the part of T4 in the blood that affects how the body’s cells work.The results of the T4 blood tests can help diagnose hyperthyroidism or hypothyroidism and guide treatment.
  • TSH test: A thyroid stimulating hormone test can help tell how well the thyroid is working. If a thyroid disease prevents the gland from making enough thyroid hormone, the pituitary gland releases more TSH into the blood. If the thyroid is making too much thyroid hormone, the pituitary releases less TSH, which can lower the levels of TSH in the blood.
  • T3 total test: The T3 total test measures the other major thyroid hormone in the blood. It often helps doctors diagnose hyperthyroidism.
  • In some cases, abnormal thyroid test results can be due to a medicine, an ongoing medical condition, or pregnancy. In these cases, there may be nothing wrong with the thyroid or pituitary glands themselves.

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    What Imaging Tests Do Doctors Use To Diagnose And Find The Cause Of Thyroid Disease

    Your health care professional may order one or more imaging tests to diagnose and find the cause of thyroid disease. A trained technician usually does these tests in your doctors office, outpatient center, or hospital. A radiologist, a doctor who specializes in medical imaging, reviews the images and sends a report for your health care professional to discuss with you.

    What Does It Mean When Your Tsh Is Low

    Low levels typically indicates an overractive thyroid gland, which produces too much thyroid hormone. This is known medically as hyperthyroidism.

    It can be caused by an autoimmune disease , goiter, excessive iodine in the body, or an overdose of synthetic thyroid hormone.

    Initial hyperthyroidism treatment can involve antithyroid medications and radioactive iodine to slow down thyroid hormone production. Most respond well to hyperthyroidism medications and are treated successfully.

    Summary: Low TSH levels for the average adult are less than 0.2 mIU/L. This reading typically indicates an overractive thyroid.

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    What About Those Already On Thyroid Medications

    If youre already on thyroid meds, but still have symptoms, you may need to up your dosage so that your labs fall within the optimal range, which in turn can help you feel better.

    Please take a look at my article on TSH for a letter that you can take to your physician if he/she is not familiar with the current optimal reference range. As I mentioned earlier, I personally feel best with a TSH a bit under 1IU/mL, but you may need some trial and error to find your personal best TSH.

    Once you establish a dose of medication thats working for you and as long as your symptoms dont change you can test your thyroid hormones every six months.

    Hypothyroidism Tests: A Measure Of Treatment Success

    Thyroid Function Tests (TFTs) – Blood tests to Diagnose Thyroid Problems – T3, T4, TSH tests

    Hypothyroidism is treated with daily medication. Taking synthetic thyroid hormone medication can bring your T4 and TSH levels back to their normal ranges. Once youre on the right dose, your symptoms should subside.

    When you first start taking medication, your doctor will need to monitor your blood to fine-tune the dosage. Initially you will need to be tested more frequently, Doria-Medina says. A person who is newly diagnosed and taking medication for hypothyroidism should be tested every six weeks until the dosage is just right.

    The dose you start with is your doctors educated guess about whats best for you most likely the lowest dose possible to avoid side effects, which can include a rapid heartbeat and restlessness.

    Medication for hypothyroidism is slow acting, and it can take several weeks for your body to adjust. If your TSH is still high and your symptoms havent subsided after 6 to 10 weeks, your doctor will likely increase the dose, and youll need your blood tested again after another 6 to 10 weeks.

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    What Does The Test Measure

    The TSH test measures thyroid-stimulating hormone, which is a hormone that prompts the thyroid to produce other hormones. The thyroid is a butterfly-shaped gland in your neck that makes the hormones triiodothyronine and thyroxine . T3 and T4 control your metabolism, or how your body uses and stores energy.

    Although TSH acts upon the thyroid gland by binding to the TSH receptor, it is made in the pituitary gland. The pituitary gland is sometimes called the master gland, because it produces many hormones that control the functions of other glands in the body. The pituitary gland is able to sense when your T3 and T4 hormone levels are too low or too high. In response, it will produce more or less TSH to stimulate your thyroid gland to produce the right amount of hormones.

    If your thyroid is underactive, you may have high levels of TSH as your pituitary gland tries to stimulate the thyroid to produce more T3 and T4. If your thyroid is overactive, your TSH may be abnormally low because your pituitary gland stops making TSH when your thyroid hormone levels are too high.

    Reason #1: The Tsh Controversy

    TSH alone is not enough to manage your thyroid condition. There is a big push in the thyroid advocacy world against the blindness of doctors of using TSH to treat thyroid patients.

    There are a few reasons for that. Firstly, the range used by conventional doctors is 0.5 5.0 whereby functional and integrative practitioners would want to see a healthy person to have their TSH in the 1-2 range.

    You see, I also had a perfect TSH of 1.6 to 1.8 even when my body was completely shutting down. This is due to reason #2, see below.

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