What Is Thyroid Peroxidase
Thyroid peroxidase is an enzyme made in the thyroid gland that is important in the production of thyroid hormone. TPO is found in thyroid follicle cells where it converts the thyroid hormone T4 to T3.
The thyroid gland is located in the lower part of the neck, below the Adam’s apple, wrapped around the trachea .
Types Of Thyroid Antibodies
The thyroid antibodies that appear most frequently are
- Antithyroid Peroxidase Antibody or TPO Ab this is also known as Antithyroid Microsomal Ab
- Antithyroglobulin Antibody or TG Ab
- Thyroid Stimulating Immunoglobulin or TSI Ab
The first group, the TPO Ab, are found raised in Hashimotos disease otherwise known as autoimmune Autoimmune “patients with autoimmune diseases frequently have antibodies circulating in their blood that target their own body tissues” thyroiditis Thyroiditis “a swelling or inflammation of the thyroid gland causing unusually high or low levels of thyroid hormones in the blood stream” . Here the cells of the thyroid gland;are attacked and slowly destroyed. Patients with these thyroid antibodies present either have Hashimotos or are going to have it with subsequent reduction of thyroid function. ” ).
The next group is the TG Ab. These levels rise as well as the TPO Ab levels in autoimmune thyroiditis, but to a lesser degree.
The third group, the TSI Ab, exert their effect by targeting the TSH receptors Receptors “a specialised cell or group of nerve endings that responds to things such as hormones” in the thyroid gland and activate them abnormally, thus stimulating the thyroid gland to overproduce thyroid hormones. This of course is Graves disease and these Thyroid Stimulating Immunoglobulins are the chief cause of it.
What Does It Mean To Have High Thyroglobulin Antibodies
If you are new to understanding thyroid labs, or even if you’ve had a thyroid condition for some time, it can be challenging to know what your doctor is testing and what these markers mean. There are several labs your thyroid doctor will likely use to assess your thyroid function. Still, this article will look specifically at thyroglobulin antibodies, known by its abbreviation TgAB or anti-Tg.
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Thyroid Antibodies An Early Warning For Hashimotos
In Hashimotos, we know there are 5 stages relating to the initial development and also worsening of the disease. A quick review of these stages is helpful in understanding the importance of knowing your thyroid lab results.
It also really demonstrates the importance of specifically knowing your results relating to the presence of elevated thyroid antibodies.
What Is Hypothyroidism And How Is It Treated
This is a condition that affects over three million people in the United States each year. This disorder results when the gland does not produce enough thyroid hormones, which contributes to a vast plethora of symptoms. While those most commonly affected by this condition are women in their 60s, people of all ages suffer from underactive thyroid, including rare cases of children as young as age two. Women, ages nineteen to forty are likely to suffer from this debilitating condition as well. Though this is treatable by medical professionals, it is not an enjoyable condition to deal with, and those affected by it demonstrate symptoms of a thyroid problem, including:
- Chronic fatigue, despite receiving a full nights rest.
- The constant feeling of being cold .
- Brittle, cracked nails that do not grow well.
- Hair loss and dry hair.
- Sexual dysfunction
- A lack of appetite, due to irregular leptin hormone levels.
- A delay in growth that stems from the delay in puberty in young adults.
- A lack of attention span and mental function.
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Stage 2: The Breakdown Of The Immune Tolerance
In the second stage, you start seeing the breakdown of the thyroids immune tolerance, and the person will start to have a white blood cell infiltration into the thyroid gland. Some of these immune cells are going to start grouping there. This;is when we will also start seeing elevated thyroid antibodies. This stage can go on for many years a decade or more before a person moves on to stage 3 or 4, when we start to actually see symptoms and changes in thyroid function.
What Are Normal Thyroid Levels
A typical thyroid test is conducted through the blood, but a vast array of other options are available if a patient should need more in-depth results. According to the 3rd edition of Clinical Methods: The History, Physical and Laboratory Examinations, a;thyroid blood test and other forms of testing tend to demonstrate the following results that constitute normality:
- Serum thyroxine: 5 to 12 nanograms per deciliter.
- Free thyroxine fraction: 0.03%
- Free Thyroxine index: 4 to 12 nanograms per deciliter.
- Serum Triiodothyronine: 80 to 180 nanograms per deciliter.
- Radioactive iodine uptake: 10% to 30%
- Thyroxine-binding globulin: 12 to 20 nanograms per deciliter.
- Serum thyroglobulin l: 0;to 30 nanograms per deciliter
A thyroid function test usually exists in favor of diagnosing problems affiliated with the glandespecially in patients who are demonstrating symptoms that might symbolize that their thyroid is administering too much T3 or T4 hormones, or even too little. Common signs affiliated with thyroid disruptions include:
- Mood swings, including anxiety.
- Sweating or consistent chills, due to the inability to adapt to temperature changes.
- Hair loss
- Trembling of the hands
- Irregular sleeping patterns
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Common Questions Patients Ask & Related Research
Falk: Whats the most common question you get from patients with thyroid disease?
Kirk: The most common question I get relates to prognosis, meaning, Whats going to happen to me and how long will it take to get better? A related question is, Why did this happen to me? I think thats not an uncommon question for any autoimmune disease. We dont have great answers. Those two questions together probably comprise most of what people ask me the first time I see them.
Falk: The common three questions I think for all people who take care of autoimmunity are,What caused my disease? How did I get it? Whats going to make it go away or make it worse? Then the other question for many of us here is, Whats going to make it never come back? Patients on thyroid replacement medicine may end up being on that medication forever, is that right?
Kirk: Thats true. People who have autoimmune hypothyroidism, or underactive thyroid, I would say the vast majority of people will need to be on some sort of thyroid replacement indefinitely. There are a small number of people who may have had a transient condition and we certainly dont need to continue medication in thembut for others it does become part of their daily routine.
Falk: In contrast, people who have hyperthyroidism or hyperactive disease, many times you can get that disease under control and no other long-term therapy is required.
Falk: What fun new research is exploring the answers to the questions that patients are raising?
How Does Each Thyroid Antibody Impact Your Body
The presence of each antibody impacts your thyroid gland in sightly different ways:
Anti-thyroid peroxidase antibodies
The presence of TPOAb is associated with Hashimotos disease.;
TPOAbs attack the healthy tissue of the thyroid gland and stop it from producing thyroid hormones. This is also know as having an underactive thyroid or hypothyroidism.;
Up to 95% of people with Hashimotos will have TPO antibodies in their blood, making them the most obvious sign that you might have or will develop Hashimotos.
Thyroglobulin antibodies are another type of antibody associated with thyroid disease.
Like TPO antibodies, TgAb are also found in people with Hashimotos disease, but to a lesser extent.;
Thyroid receptor antibodies
This group of antibodies target the Thyroid Stimulating Hormone receptors in the Thyroid gland. This can cause the gland to overproduce Thyroid hormones, resulting in an overactive Thyroid ; or hyperthyroidism.;
Hyperthyroidism can lead to Graves disease, and the TRAb are the root cause.;
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Data Collection And Laboratory Measurements
In order to accurately obtain clinical data during medical examination, interviewers were trained specially. Body weight and height were measured with an automatic body composition analyzer and BMI was calculated. Systolic blood pressure and diastolic blood pressure were recorded at rest.
A fasting blood sample was collected. HbA1c, triglycerides , and high-density lipoprotein cholesterol levels were also measured using standard procedures at SRL, Inc. ; HbA1c and TG levels were measured by the enzyme method while the HDLc level was measured by the direct method. TSH, free T3, free T4, and TPO-Ab were measured by standard procedures at the LSI Medience Corporation ; TSH, free T3, and free T4 were measured by chemiluminescence immunoassay, and TPO-Ab was measured by electrochemiluminescence immunoassay.
A normal range of TPO-Ab was defined as below 16IU/mL. Maximum values for the left and right common carotid arteries of the CIMT were calculated with an semiautomated digital edge-detection software following a protocol that has been described in detail elsewhere. The higher values of the right and left CIMT not including plaque measurements were then calculated, and the maximum CIMT value was then used for analysis. Since a previous study reported the normal CIMT value as <1.1 mm, we defined atherosclerosis as CIMT 1.1 mm.
How Does The Thyroid Gland Function
The major thyroid hormone secreted by the thyroid gland is thyroxine, also called T4 because it contains four iodine atoms. To exert its effects, T4 is converted to triiodothyronine by the removal of an iodine atom. This occurs mainly in the liver and in certain tissues where T3 acts, such as in the brain. The amount of T4 produced by the thyroid gland is controlled by another hormone, which is made in the pituitary gland located at the base of the brain, called thyroid stimulating hormone . The amount of TSH that the pituitary sends into the bloodstream depends on the amount of T4 that the pituitary sees. If the pituitary sees very little T4, then it produces more TSH to tell the thyroid gland to produce more T4. Once the T4 in the bloodstream goes above a certain level, the pituitarys production of TSH is shut off. In fact, the thyroid and pituitary act in many ways like a heater and a thermostat. When the heater is off and it becomes cold, the thermostat reads the temperature and turns on the heater. When the heat rises to an appropriate level, the thermostat senses this and turns off the heater. Thus, the thyroid and the pituitary, like a heater and thermostat, turn on and off. This is illustrated in the figure below.
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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.
What More Should I Know About Thyroid Blood Tests
Ranges noted here are approximate; your providers may differ slightly. Its important that you remember abnormal readings do not necessarily mean a thyroid disorder is present, as each test can be affected by a variety of factors.
No preparation is required for these tests. They can be taken any time of day without fasting.
Last reviewed by a Cleveland Clinic medical professional on 12/27/2019.
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Immunologic Processes In Aitd
Figure 2. Pathogenesis of Hashimotos disease and GD . Autoreactive CD4+ T cells in HT induce antibody production by B cells. The antibodies bind to the basal membrane of the thyroid follicle, activate complement, and induce necrosis of thyrocytes. The activation of cytotoxic CD8+ T cells leads to the induction of apoptosis by action of perforin. Finally, the expression of Fas and FasL by thyrocytes perpetuates HT. Autoreactive CD4+ T cells in GD induce only anti-thyroid-stimulating hormone receptor antibody-producing B cells. These antibodies act stimulatory by increasing I2 metabolism and promoting proliferation and survival of thyrocytes. Blocking antibodies are characterized by lack of effect , and neutral antibodies activate various pathways, such as PI3K/Akt, mTOR/p70S6K, and MAPK/ERK1/2 and induce thyrocyte apoptosis. Abbreviations: GD, Graves disease; HT, Hashimotos thyroiditis; ERK, extracellular signal-regulated kinase; MAPK, mitogen-activated protein kinase; p70S6K, ribosomal protein S6 kinase beta-1; PKC, protein kinase C; PI3K, phosphatidylinositol 3,4,5, triphosphate kinase; PKA, protein kinase; mTOR, mammalian target of rapamycin.
What Is A Thyroglobulin Antibody
Let’s make this super easy:
Thyroglobulin is an important protein found directly in your thyroid gland.;
This protein plays an important role in helping your body CREATE thyroid hormone, STORE thyroid hormone, and RELEASE; thyroid hormone.;
Thyroglobulin antibodies are antibodies that your own immune system creates which ATTACK this particular protein.;
You can imagine how this would be a problem for your thyroid gland if your own body is attacking it .;
If present, they often indicate both an immune problem AND a thyroid problem which is why they are so important.;
They indicate an immune problem because your immune system should not be attempting to destroy your own body and they indicate a thyroid problem because eventually, your own body will destroy your own thyroid gland.;
These antibodies float around in your blood and target your thyroid which results in both inflammation and damage over time.
This damage eventually adds up to prevents the release of thyroid hormone which causes hypothyroidism or low thyroid function.;
The good news is that you can TEST for these antibodies which gives you powerful insight as to what is happening to both your thyroid gland and your immune system.;
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Clinical Information Discusses Physiology Pathophysiology And General Clinical Aspects As They Relate To A Laboratory Test
Thyroperoxidase is an enzyme involved in thyroid hormone synthesis, catalyzing the oxidation of iodide on tyrosine residues in thyroglobulin for the synthesis of triiodothyronine and thyroxine . TPO is a membrane-associated hemoglycoprotein expressed only in thyrocytes and is one of the most important thyroid gland antigens.
Disorders of the thyroid gland are frequently caused by autoimmune mechanisms with the production of autoantibodies. Anti-TPO antibodies activate complement and are thought to be significantly involved in thyroid dysfunction and the pathogenesis of hypothyroidism.
The determination of TPO antibody levels is the most sensitive test for detecting autoimmune thyroid disease and detectable concentrations of anti-TPO antibodies are observed in most patients with these disorders. The highest TPO antibody levels are observed in patients suffering from Hashimoto thyroiditis. In this disease, the prevalence of TPO antibodies is about 90% of cases, confirming the autoimmune origin of the disease. These autoantibodies also frequently occur in the course of Graves disease.
In patients with subclinical hypothyroidism, the presence of TPO antibodies is associated with an increased risk of developing overt hypothyroidism. Many clinical endocrinologists use the TPO antibody test as a diagnostic tool in deciding whether to treat a patient with subclinical hypothyroidism, and Mayo Clinic Laboratories endorses this practice.
Why Are Thyroid Antibodies Important
Keeping track of your antibody levels helps you understand if youre at risk of thyroid disease.
Also, autoimmune conditions are associated with one another. If you have a diagnosis of Hashimotos you might also be at risk of developing diseases including type 1 diabetes, Addisons, coeliac disease and pernicious anaemia.
The presence of antibodies to the thyroid may prompt your clinician to screen for these other diseases depending on your symptoms.
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How Is The Tpo Antibodies Test Performed
TPO antibodies test is, basically, a blood test. Your healthcare provider or a lab technician will take a sample of your blood in order to measure how many antibodies are in it.
The blood sample is collected by inserting a needle into a vein in the arm. You might feel a little sting when the needle goes in or out. The whole process lasts five minutes maximum. TPO antibodies test requires no special preparations.
However, you should inform the doctor if you’re taking some medications, supplements, or herbs. Some drugs and supplements may impair the results.
Based on the information you provide, the doctor will suggest whether you can continue taking the medication or supplement even on the day of the test or not.
Follow the doctors recommendations religiously in order to get accurate results and precise diagnosis or insight into your condition.
Too Much Synthetic T4 Hormones
Thyrotoxicosis factitia is a condition caused by taking too much synthetic T4 hormones . It mimics an extremely overactive thyroid. Thyroglobulin levels are very low or undetectable in people with this condition .
Thyroglobulin can help doctors determine if an overactive thyroid is due to TF or other causes .
Make sure to use levothyroxine only if your doctor prescribed it, and strictly follow their dosage instructions.
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T3 And T4 Interpretations
- A normal TSH and normal T4 indicates a normally functioning thyroid gland.
- A low TSH and high T4 generally indicates hyperthyroidism.
- A high TSH and low T4 indicates primary hypothyroidism .
- A low TSH and low T4 suggest secondary hypothyroidism .
For diagnostic purposes, a low T3 value accompanied by a high TSH value is considered evidence of hypothyroidism. By contrast, a low TSH value accompanied by a high T3 value is considered evidence of hyperthyroidism.
Different Types Of Autoimmune Thyroid Disease
Falk: What on earth is autoimmune thyroid disease?
Kirk: Autoimmune thyroid disease is a complex term. Its not really one disease. Its rather a term that refers to a number of different ways that the immune system could affect the thyroid gland.
Falk: Where is the thyroid?
Kirk: The thyroid is on the base of the neck in the midline, so if you were to take your fingers and press right at the bottom of the neck, you probably wouldnt feel it because most thyroid glands are difficult to feel. Its about 4 centimeters tall on either sideits the shape of a butterfly, we like to say. Thats where its located.
Falk: So that organwhat is the thyroid supposed to do in the first place?
Kirk: The thyroid does a lot of things. It produces thyroid hormones. These hormones affect essentially every cell in the body. A simple way to think about what thyroid hormone does, is it is a contributor to metabolism and activity so it may rev up the system, so to speak. If its produced in appropriate quantities it keeps many organs and systems in equilibrium.
Falk: So if your thyroid is overworking or hyperactive, how do you feel?
Kirk: If your thyroid is overactive or if youre producing too much thyroid hormone you may lose weight without meaning to, you may be very hot, you may be sweaty, anxious, or have tremors that you or others may notice. We often hear people say that they have rapid heartbeat or fluttering sensation which we refer to as palpitations.
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