Your body creates thyroglobulin antibodies when it mistakes thyroglobulin as a threat. Testing the levels is useful in thyroid cancer patients and those with other thyroid disorders. Learn about the causes and effects of high levels + factors that reduce them.
In order to understand what thyroglobulin antibodies (TgAb) are, we first have to talk about thyroglobulin (Tg) itself.
The immune system may mistakenly identify thyroglobulin as a harmful substance. In turn, it produces antibodies to attack thyroglobulin, otherwise known as TgAb .
According to some estimates, about 10% of the general population produces at least some TgAb. This rate goes up to 80% in those with thyroid disorders, such as in Hashimoto’s or Graves’ disease. That’s why TgAb are used as a marker of autoimmune thyroid problems [1, 2, 3].
Thyroglobulin antibodies can bind to thyroid cells, but it’s not entirely clear if they cause damage. These antibodies mostly become a problem when trying to measure thyroglobulin, as they skew thyroglobulin test results [1, 3, 4, 5].
The TgAb test can help pinpoint autoimmune thyroid disorders, such as Graves’ disease and Hashimoto’s Thyroiditis. Your doctor may order the test if you have signs or symptoms of a thyroid disorder. Some symptoms of hypo- and hyperthyroidism may overlap. For example, both can cause thyroid gland enlargement and neck swelling [3, 4, 6].
On the other hand, typical symptoms of an overactive thyroid (hyperthyroidism) include :
- Weight loss
- Anxiety or nervousness
- Increased sweating
- Heart palpitations
- Muscle weakness
- Heat intolerance
The TgAb test requires a blood sample. Results are reported as a number in units of IU/mL.
These two tests are done together because TgAb interferes with thyroglobulin measurements, resulting in falsely low levels. TgAb testing helps doctors determine the extent of interference. However, since this interference varies from person to person, estimating the true thyroglobulin levels can still be challenging [8, 9].
The body should not be producing any TgAb .
However, even people without any thyroid issues may produce someTgAb. In healthy people, TgAb does not cause any problems .
Often times, the TgAb results will come back as 1.0 IU/mL. This may be the actual TgAb level, or it could be that the test isn’t sensitive to detect levels lower than that.
TgAb levels below 20 IU/mL are typically considered normal for the general population (those without any thyroid issues). However, the normal range can greatly vary depending on the test manufacturer .
The optimal range for people with thyroid conditions is even less clear. Higher levels point to autoimmune thyroid disorders. Research also suggests TgAb levels above 40 IU/mL may be associated with an increased risk of thyroid cancer .
In people who had thyroid cancer, thyroglobulin levels should be as low as possible. Any increases suggest the cancer is coming back or there is leftover thyroid tissue. Newer studies suggest that thyroglobulin antibody levels should also be as low as possible .
According to a recent study, thyroid cancer survivors with TgAb levels that fall by 50% (or more) by one year after treatment are at a lower risk of the cancer coming back. Patients whose TgAb levels didn’t change or increased over this period of time had higher rates of cancer recurrence .
Thyroid peroxidase antibody (TPOAb) is very similar to TgAb: it is also an antibody that mistakenly attacks the thyroid gland. While TgAb targets thyroglobulin, TPOAb targets an important thyroid enzyme called thyroid peroxidase. TPOAb can increase oxidative stress and may damage the thyroid .
The TBOAb test is also sometimes called the Antithyroid Microsomal Antibody Test (or just antimicrosomal antibodies test).
About 90-95% of people with autoimmune thyroid disorders have detectable TPO antibodies, while only 70-80% of them have detectable thyroglobulin antibodies. Therefore, your test results may come back as normal TgAb and detectable TPOAb even if you have autoimmune thyroid issues .
TPOAb assays vary in sensitivity. Older assays may not detect TPO antibody levels more sensitive assays would. If your TPOAb came back normal (undetectable) and your TgAb high, you should probably repeat the TPO test with a more sensitive assay [14+].
People without thyroid problems may also test positive for TPOAb. According to some estimates, about 10 to 15% of the general population produce TPOAb .
Another big difference between these two types of antibodies is that TPOAb does not interfere with thyroglobulin tests like TgAb does. This means a TPOAb test would not be helpful for determining thyroglobulin levels .
TgAb levels are a marker of thyroid health. Low or high levels don’t necessarily indicate a problem if there are no symptoms or if your doctor tells you not to worry about it.
If you have an underlying thyroid condition, high thyroglobulin antibodies may be associated with the symptoms of that condition. According to one study, those with high TgAb and Hashimoto’s thyroiditis will experience more :
- Face and eye swelling
- Fragile hair
- Voice changes
Autoimmune diseases occur when the body’s immune system mistakenly attacks its own tissues .
A number of autoimmune conditions can elevate TgAb, particularly those affecting the thyroid gland .
For instance, TgAb is found in about 80% of people with Hashimoto’s thyroiditis, the most common autoimmune thyroid disorder. This condition causes thyroid gland inflammation, eventually leading to hypothyroidism .
Graves’ disease is another autoimmune disorder that attacks the thyroid and results in hyperthyroidism. About 20-40% of people with Graves’ disease have high TgAb levels .
Non-thyroid autoimmune disorders may also trigger the production of TgAb .
According to several studies, over 50% of systemic sclerosis patients and 30% of rheumatoid arthritis patients have high TgAb levels. Systemic sclerosis is a rare autoimmune disease in which too much collagen and other proteins are produced [16, 17, 18].
Another example is in Sjogren’s syndrome, an autoimmune disorder that attacks the glands that produce tears and saliva. People with Sjogren’s are 9x more likely to have a thyroid-related autoimmune disorder, which is likely to raise TgAb [19, 20].
Hives are a type of skin rash caused by an allergic reaction or infection. The exact cause often remains unknown and may involve autoimmunity .
In one study of 245 people with normal thyroid hormone levels and suspected obstructive sleep apnea, almost 50% were diagnosed with Hashimoto’s thyroiditis due, in part, to high TgAb levels. Those with worse sleep apnea symptoms were more likely to be positive for TgAb .
Gender appears to play a role as well. In general, women are 10 times more likely to be affected by Hashimoto’s than men. But men are more likely to develop apnea-related Hashimoto’s than women [25, 24].
Polycystic ovary syndrome (PCOS) is a hormonal disorder that leads to irregular or no menstrual periods, acne, and difficulty getting pregnant .
These symptoms are due to high levels of androgens (male sex hormones) in women. But some researchers think PCOS may have an autoimmune basis. They discovered a strong link between PCOS and autoimmune thyroid conditions [26, 27].
For example, one study of 343 women revealed that about 27% of those with PCOS test positive for thyroid antibodies .
When most people think of vitamin D, they think of its benefits to bone health. Some know it’s good for mood as well. But this vitamin also plays a key role in the immune system. Deficiencies in vitamin D are linked to immune disorders, including autoimmunity .
In fact, iodine deficiency is one of the leading causes of hypothyroidism worldwide .
But more is not always better with iodine. In a trial of 752 people, high doses of iodine (1.53 mg each week) increased levels of TgAb .
On the flip side, low dose iodine (200 micrograms daily) actually reduces TgAb levels .
Dental amalgams may trigger an autoimmune response and increase TgAb. These “silver” dental fillings are made from a mix of metals, including mercury, silver, and copper. Their use in the U.S. is declining, but they are still the most common type of dental filling in Canada today .
People with dental amalgams may have elevated TgAb levels, according to one study. Average TgAb levels were cut in half after removing the fillings, but only in those who tested positive for mercury hypersensitivity. Up to 15% of the population is highly sensitive to chemical toxins like mercury [34, 35].
In a study of over 5,600 Chinese adults, women exposed to more cadmium had higher thyroglobulin antibody levels. Interestingly enough, heavy metal exposure did not affect TgAb levels in men .
Women with Turner’s syndrome are completely or partially missing an X chromosome. This leads to a number of health problems, including thyroid dysfunction .
In a study of 89 girls, thyroid antibodies were detected in about 52% of those with Turner’s syndrome. Girls with more severe forms of the disorder were more likely to have high TgAb .
Hepatitis C is a viral infection that attacks the liver. Research suggests an important link between hepatitis C and the risk of autoimmune thyroid disorders .
According to a review of 12 studies, people with hepatitis C are 2.4x more likely to test positive for TgAb .
Your genes may affect your thyroglobulin antibodies and thyroid health .
One study explored this genetic effect by looking at 686 sets of twins. They discovered that the influence of genetics on TgAb levels is about 39% in men and 75% in women .
Several medications may raise TgAb. Many of these drugs are cancer treatments that alter the immune system in some way.
Some examples of drugs that can raise TgAb levels include:
- Interferon-α (Multiferon) 
- Nevirapine (Viramune) 
- Nivolumab (Opdivo) 
- Triptorelin (Trelstar) 
- Radioactive iodine therapy 
A study of 290 people with Hashimoto’s thyroiditis revealed that higher levels of TgAb are associated with an increased number and severity of symptoms .
Thyroid nodules are small lumps that can form in the thyroid gland (near the base of the neck) .
In one study of 1,271 adults, those with higher levels of TgAb were at a higher risk of developing thyroid nodules. The association was stronger in women .
On top of that, thyroid nodules are more likely to be cancerous in those with high TgAb .
According to a study of over 1,600 people, high levels of TgAb (≥40 IU/mL) are linked to increased rates of thyroid cancer (differentiated thyroid carcinoma) .
As mentioned in the previous section, TgAb may also increase the risk of cancerous thyroid nodules .
In vitro fertilization (IVF) is the process of fertilizing a human egg in the lab. The procedure is a great option for couples with fertility issues.
However, women who test positive for thyroid antibodies may want to do additional screenings if considering IVF.
Based on a study of 766 women, those who have thyroid antibodies have worse IVF outcomes. This includes lower fertilization and pregnancy rates, as well as a higher risk of miscarriages .
TgAb levels may influence normal pregnancies as well.
Mothers who are positive for TgAb give birth to infants with lower birth weights, according to a study of over 7,600 women .
Women with TgAb may also be more likely to have their “water break” prematurely, a condition known as prelabor rupture of membranes .
Improving your TgAb levels won’t necessarily cause improvement in thyroid health, but it can be used as a biomarker. The following is a list of complementary approaches to support the thyroid that may also balance high TgAb levels.
Though studies suggest various dietary and lifestyle factors may lower TgAb levels, additional large-scale studies are needed. Remember to talk to your doctor before making any major changes to your day-to-day routine.
One clinical trial gave 50,000 IU of vitamin D for a week to 42 women with Hashimoto’s thyroiditis. After 3 months, vitamin D supplementation reduced TgAb levels by an average of 50 IU/mL .
Another study using a smaller vitamin D dose of 2,000 IU daily found a similar (but smaller) reduction in TgAb .
The best way to increase your vitamin D levels is to get more sun. Beyond vitamin D, sun exposure can balance the immune system and provide you with a number of other benefits. Studies have yet to examine its effects on TgAb, though .
For example, weekly iodine doses of 1.53 mg increased TgAb levels .
On the other hand, a much lower dose of 200 micrograms daily (equivalent to 0.2 mg) significantly reduces TgAb .
Some good dietary sources of iodine include :
- Dairy products
- Iodized salt
According to a study of 88 women, a selenium dose of 200 micrograms each day decreases TgAb levels .
However, a dose of 100 micrograms had a weaker effect that diminished over time .
Some good sources of selenium include :
- Brazil nuts
- Whole grains
Diet plays an important role in many conditions, and thyroid disorders are no exception.
A recent study revealed that a low-carb, protein-rich diet reduces TgAb levels by about 40% .
Dental amalgam fillings may trigger a rise in TgAb and autoimmunity .
One study reveals that removing this type of metal filling decreases TgAb levels in people who are hypersensitive to mercury .
Have a talk with your dentist and doctor to weigh the potential benefits of replacing your amalgam fillings with mercury-free ones.
Emerging research suggests TgAb plays an important role in thyroid disorders, but studies remain limited .
The effects TgAb has on healthy people or on those with a thyroid disorder are not fully understood. TgAb is associated with many conditions, but it’s not always clear if high TgAb levels are a causal factor or result of thyroid disorders [5, 65].
Your doctor may order a thyroglobulin antibody (TgAb) test to check for thyroid cancer or autoimmune thyroid disorders. High TgAb is common in people with thyroid issues. Excess levels may increase the risk of certain pregnancy complications and worsen thyroid symptoms.
You may also test positive for TgAb even if you are healthy. This is usually not a reason for concern. To lower your TgAb naturally and support the thyroid, get adequate amounts of vitamin D, iodine, and selenium. Eating a low-carb diet and removing amalgam dental fillings may also help.