What Does The Test Measure
Thyroid antibody testing detects and measures thyroid antibodies in the blood. Normally, antibodies attack foreign substances in the body, like bacteria, viruses, parasites and toxins.
In patients with autoimmune disorders, antibodies mistakenly target the bodys own tissues. These antibodies that attack the patients own body are also known as autoantibodies or antithyroid antibodies. Thyroid antibody testing may look for several types of thyroid antibodies:
- Thyroid peroxidase antibodies : Thyroid peroxidase is an enzyme that is crucial to the production of thyroid hormones. TPOAb may interfere with the action of this enzyme. Almost all patients with Hashimotos thyroiditis have high levels of TPOAb.
- Thyroglobulin antibodies : Thyroglobulin is a protein made by the thyroid gland. TgAb may be present when the thyroid has been damaged. Thyroglobulin antibodies are often measured in addition to thyroglobulin tests after a patient completes treatment for thyroid cancer.
- Thyrotropin receptor antibodies : TRAb are antibodies that bind to the receptors on thyroid cells normally activated by thyroid-stimulating hormone . In Graves disease, an antibody called thyroid stimulating immunoglobulin binds to the TSH receptor and mimics the action of TSH. This causes constant stimulation of the thyroid gland, prompting it to release too much thyroid hormone into the bloodstream. Stimulation by TSI can also cause abnormal growth of the thyroid gland.
What Do The Results Mean
Your results may show one of the following:
- Negative: no thyroid antibodies were found. This means your thyroid symptoms are probably not caused by an autoimmune disease.
- Positive: antibodies to TPO and/or Tg were found. This may mean you have Hashimoto disease. Most people with Hashimoto disease have high levels of one or both of these types of antibodies.
- Positive: antibodies to TPO and/or TSH receptor were found. This may mean you have Grave’s disease.
The more thyroid antibodies you have, the more likely it is that you have an autoimmune disorder of the thyroid. If you are diagnosed with Hashimoto disease or Grave’s disease, there are medicines you can take to manage your condition.
Learn more about laboratory tests, reference ranges, and understanding results.
Are There Any Risks Of Tpo Antibodies Test
Generally speaking, the TPO antibodies test is safe and is not associated with some severe risks.
However, some patients may experience bleeding, bruising, feeling of lightheadedness, and infection. The likelihood of these minor risks is small, and it doesn’t mean that all patients will experience them.
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What Is Tpo Antibodies
TPO, otherwise known as thyroid peroxidase, is an enzyme that usually exists in our thyroid gland. One of its major roles is to produce thyroid hormones. The thyroid gland is a butterfly-shaped one that is located in our throat. It produces many hormones such as T3 and T4. These two are very important to help the body use the energy it needs and metabolize properly. Our body resorts to a feedback system where a hormone called TSH controls the production of T4 and T3, as needed by the body. It helps stabilize the thyroid hormones in our blood.
Thyroid antibodies start forming when our immune system targets some parts of the thyroid gland or thyroid proteins, by mistake. As a result, chronic inflammation of the thyroid, referred to as thyroiditis, happens, along with many other conditions like tissue damage and degradation of thyroid function. This is called an autoimmune disorder that can be associated with hypothyroidism and hyperthyroidism. Such autoimmune conditions include Hashimoto thyroiditis and Graves disease.
Hashimoto thyroiditiss exact causes are not fully understood. But, many risk factors can contribute to such a diagnosis like having the genetic component of the disease. Gender plays a major role in the incidence of this condition: women are seven times more likely to suffer from it. Many drugs and having a high Iodine intake can trigger malfunctions of the thyroid gland, especially among those who are already susceptible.
Thyroid Antibodies You Are Most Likely To Test Positive For
Many of you have read about thyroid antibodies Antibodies “protein produced in the blood that fight diseases by attacking and killing harmful bacteria” , or seen them mentioned in your blood tests. Because it sounds pretty technical, some of us get a bit confused about the whole thing so here is an explanation.
You know that the body produces antibodies as part of a normal immune response to foreign invaders, like viruses and bacteria. It happens that certain body proteins Proteins “plant or animal tissue” , going peacefully about their business, can get attacked by the immune system Immune system “the organs and processes in the body that work together to resist infections” , even if they have done nothing wrong. When this happens the body cells being wrongly attacked can be damaged and destroyed. This can happen in a number of ways, but we, of course, are most interested in the thyroid.
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Thyroid Peroxidase Antibodies Test And Who Needs It
Thyroid peroxidase antibodies test measures the level of an antibody that is directed against TPO.
These antibodies are produced in the body by the immune system, as mentioned above.
The TPO antibodies test serves multiple purposes, such as:
- Helping doctors diagnose autoimmune thyroid disorders
- Aiding in differentiating autoimmune thyroid disorders from non-autoimmune hypothyroidism or goiter
- Serves as a diagnostic tool in deciding whether to treat a patient who has been diagnosed with subclinical hypothyroidism
Doctors may also order a TPO antibodies test if you are pregnant and have an autoimmune disease, particularly the condition that involves thyroid.
Thyroid peroxidase antibodies have been associated with reproductive difficulties such as miscarriage, preeclampsia, premature delivery, and in-vitro fertilization failure. In these instances, the doctor may also order TPOAbs test, but bear in mind its not a standard test for problems with fertility and pregnancy.
If a pregnant woman has an autoimmune thyroid condition or some other autoimmune disease with thyroid involvement, the doctor may order TPO antibodies test in order to determine whether the baby could be at risk of thyroid dysfunction.
Additionally, you might need a TPO antibodies test if other thyroid hormone levels are too low or too high. Your doctor will need results from TPO antibodies test to determine whether an autoimmune condition impaired the production and concentration of thyroid hormones.
Conditions Associated With High Thyroid Peroxidase Antibodies
What does it mean if you have thyroid peroxidase antibodies floating around in your blood?
Well, it can mean several things:
- It may be a marker for the autoimmune disease known as Hashimotos thyroiditis.
- It may also be a marker for another autoimmune disease of the thyroid gland known as Graves disease .
- It may be a transient thing that may eventually go away on its own ).
The presence of thyroid peroxidase antibodies is never normal but it doesnt always guarantee a poor outcome.
For instance, as I mentioned above, some people see elevated antibodies during pregnancy which then fall after birth.
The significance of thyroid peroxidase in this exact setting is not well understood but it does give some hope that not every situation of elevated antibodies points to autoimmune disease.
Why would you want to check your thyroid peroxidase antibodies?
Your doctor can use this test in a number of useful ways:
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Associations Between The Grs And Thyroid Ultrasound Findings
Supplemental Table 7 shows a graded and significant association between higher GRS and lower thyroid volume in SHIP-0, which was not observed in SHIP-T. There was a significant inverse association across quartiles of the GRS with lower odds of goiter in SHIP-0 , which was also not observed in SHIP-T. Low echogenicity did not show an association with the GRS in either SHIP-0 or SHIP-T.
Factors Linked To Thyroid Autoimmunity
Autoimmune thyroid diseases are usually accompanied by the presence of anti-thyroid peroxidase , anti-thyroglobulin , and anti-thyroid-stimulating hormone receptor antibodies. Antibodies against thyroid antigens such as carbonic anhydrase 2, megalin, T3 and T4, sodium iodide symporter , and pendrin have also been detected, although rarely .
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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.
Identification Of Associated Genetic Variants And Genotyping Information
To identify TPOAb-associated single nucleotide polymorphisms that could be combined into a GRS, we used information from a recently published large GWAS meta-analysis of TPOAb concentrations and positivity, to which the SHIP studies contributed but the ARIC study did not . The study reported 20 index SNPs associated with measures of AITD at P< 106 . In the ARIC study, genotypes at these SNPs were available from the Affymetrix Genome-Wide Human SNP Array 6.0. Quality control procedures and genotype imputation were described previously . The published effect estimates for the 20 index SNPs were meta-analyzed with the corresponding SNP estimates and traits from the ARIC study using a sample-size weighted meta-analysis as implemented in METAL . Subsequently, genotypes of all previously identified replicated loci and newly identified genome-wide significant index SNPs were used for the calculation of the GRS. Genotyping and imputation quality of the SNPs studied in this report are listed in Supplemental Table 3.
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Immunologic Markers In Diagnosis
TG and TPO antibodies provide readily available evidence for Graves’ disease although not specific, their presence in a patient with hyperthyroidism strongly suggests the diagnosis. TSAb are not generally measured because present bioassays are laborious. TBII estimation is a commercially available surrogate but these antibodies are absent in some newly diagnosed patients and present in AT patients who have TSH-R blocking antibodies. TSAb or TBII levels have been investigated as predictive markers for the success of antithyroid drug treatment in Graves’ disease. Although patients with the highest levels tend to relapse the most, the results are insufficiently accurate for clinical use . The most important indication for TSAb assay in Graves’ disease is during pregnancy to predict the risk of neonatal thyrotoxicosis .
Anthony P. Weetman, in, 2014
I Found Out My Thyroglobulin Antibody Is High Now What
Despite thyroglobulin antibody levels showing a correlation with thyroid health, research supports that they are not a strong predictor of thyroid disease. There are much more reliable tests for diagnosing Hashimotos thyroiditis, such as TPO-antibodies, TSH levels, and thyroxine levels.
Hashimotos thyroiditis is a common autoimmune condition that causes the immune system to attack the thyroid gland. In some cases, this leads to hypothyroidism, however this is much less common than many people assume .
Hashimotos is diagnosed by several thyroid function tests, such as [1
- Low thyroid hormone levels, reported as free or total T3 and T4
- Elevated thyroid peroxidase antibodies
- Elevated thyroglobulin antibodies
- Elevated TSH antibodies
While TPO-antibodies are more indicative of Hashimotos thyroiditis, elevated anti-TG antibodies are often reported on lab results, creating concern for patients.
A 2019 study found that anti-TG antibodies are elevated in 60-80% of patients with Hashimotos thyroiditis and in 40-60% of those with Graves disease. However, the presence of thyroglobulin antibodies showed only a low-to-moderate sensitivity in diagnosing autoimmune thyroiditis. Additionally, they were not useful in identifying when a patient has transitioned from subclinical to overt hypothyroidism .
It is no wonder that these elusive antibodies cause so much confusion to health care providers and patients.
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Is There Anything Else I Need To Know About A Thyroid Antibodies Test
Thyroid disease can get worse during pregnancy. This can harm both the mother and her unborn baby. If you have ever had thyroid disease and are pregnant, you may be tested for thyroid antibodies along with tests that measure thyroid hormones. Medicines to treat thyroid disease are safe to take during pregnancy.
What Do The Results Of Tpo Antibodies Test Mean
The TPO antibodies test results may show one of the following options:
- Negative as you can already conclude negative TPO antibodies test result indicates that no thyroid antibodies were found. This result also implies that thyroid problems and symptoms a patient experiences are not caused by an autoimmune condition
- Positive antibodies to TPO and/or Tg this result indicate a patient may have Hashimotos thyroiditis
- Positive antibodies to TPO and/or TSH may indicate the presence of Graves disease
The higher the level of antibodies, the more likely it is that a patient has an autoimmune disease of the thyroid e.g., Hashimoto’s or Graves’ disease. Blood test results for TPO antibodies are positive in 95% of patients with Hashimotos thyroiditis and in 50% to 80% of people with Graves disease.
When it comes to TPOAbs, the reference value is < 9.0 IU/ml . Values above 9.0 are typically associated with autoimmune thyroid disease, but elevations are also observed in some other autoimmune conditions. The most commonly mentioned TPOAb reference range is less than 35 IU/ml.
The presence of TPOAbs in patients with subclinical hypothyroidism predicts an elevated risk of overt hypothyroidism. Moreover, this also shows that those patients could be at a higher risk of developing other autoimmune conditions like type 1 diabetes.
As mentioned above in the article, some people may be positive to TPO antibodies, but they do not have a thyroid condition.
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How Are Thyroid Antibodies Tests Different From Thyroid Function Tests
Both thyroid antibodies tests and thyroid hormone tests can help diagnose common thyroid disorders. However, thyroid antibodies are made by the immune system, and thyroid hormones are made by glands that are part of the bodys endocrine system.
Thyroid function tests measure thyroid hormones, such as thyroid-stimulating hormone , T3 and T4, provide a snapshot of how well the thyroid is functioning. These tests reveal when the thyroid is underactive or overactive.
Thyroid antibodies can interfere with the way the thyroid functions, often causing it to be either underactive or overactive. The presence of specific antibodies can reveal the root cause of a thyroid disease.
What Do Tpo Antibodies Mean To You
TPO antibodies test informs the doctor whether symptoms you experience are associated with an autoimmune condition. But, if you already have some thyroid disease, its treatment is not really based on antibody levels.
After all, the treatment of thyroid condition is based on thyroid hormone levels and the severity of symptoms a patient experiences. Doctors order TPO antibodies tests to assess the potential cause of thyroid condition and identify the subclinical disease of the butterfly-shaped gland.
The doctor is less likely to treat the thyroid disease if a patient has high TPO antibodies without symptoms and with normal thyroid hormone levels. On the other hand, if a patient has mild symptoms or borderline abnormal thyroid hormone levels along with higher TPO antibodies, the doctor may recommend treatment. Again, the treatment will work to manage symptoms and normalize levels of thyroid hormones.
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What Is A Normal Level For Thyroid Peroxidase Antibodies On My Lab Tests
When you get your thyroid peroxidase lab results you will see a range of what is considered normal.
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Association Of Tai And Subfertility In Women
TAI identified by the existence of thyroid peroxidase antibodies or thyroglobulin antibodies is frequently stated in subfertile women. Specifically, TPOAb has been related to lower fertilization rates and unstable embryogenesis.13
TPOAb was likely to be positive in euthyroid women having female factor infertility in comparison with fertile, age-matched euthyroid women.6 In women with polycystic ovarian syndrome , the frequency of TAI may be higher in comparison with controls.14 In subfertile women with PCOS, the existence of TAI has been correlated with a lower probability of maturing ovarian follicles with the use of clomiphene citrate for ovulation induction.15 However, other studies have failed to prove such associations. Among infertile women with PCOS, a study conducted on 436 women undergoing 530 antral follicular count measurements, no correlation was found with regard to thyroid function or TPOAb positivity with AFC.16 Conversely, the same study reported that lower free T3 and TPOAb positivity were coupled with a lower AFC in females with diminished ovarian reserve or UE infertility.16
Gregory Kline MD, Hossein Sadrzadeh PhD, in, 2017
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