The Thyroid Antibody Test is often a cause for concern. A Thyroid Antibody Test also called Thyroid Microsomal Antibody or Thyroid Peroxidase Antibody is usually done to either confirm the cause of Hypothyroidism or predict the future risk of developing hypothyroidism. The normal level of the thyroid antibody test differs depending on the laboratory or the technique used to measure it. The thyroid antibody does not lead to any symptoms. Repeated testing of the thyroid antibody is not recommended, nor is any medication needed to lower the levels if high. The thyroid antibody levels have been linked to increased risk of pregnancy losses or may point to other associated autoimmune conditions, which may need further evaluation and discussion with your Endocrinologist.

All you need to know about a thyroid antibody test and what it means for your hypothyroidism symptoms!!


People often come to me in a state of panic because they have been asked to do a Thyroid Antibody Test by their treating doctor, and their results are remarkably high. They often do not know why they have been asked to do the Thyroid Antibody Test or what it means for their health. They turn to the internet but often end up getting more confused or scared. 

An empowered, informed person is more likely to have better health outcomes.  I fully endorse a patient’s right to look for more information on their condition, and it is up to us as health care professionals to get the right information out there. 

In this article, I will explain what a Thyroid Antibody Test is, why is it done and what it means for your health. 

  1. Why has my doctor asked me to do a thyroid antibody test?  
  2. What is the thyroid antibody normal range?
  3. My antibodies are positive; what does it mean? 
  4. How does the thyroid antibody test relate to my hypothyroidism? 
  5. My thyroid antibody levels are high; do I test them again?
  6. How do I lower my thyroid antibody levels?
  7. How does the thyroid antibody relate to pregnancy?
  8. What other conditions are linked with thyroid antibody?
  9. Is there any link between thyroid antibody test and cancer?

1.Why has my doctor asked me to do a thyroid antibody test?  

  • Confirm the cause of Hypothyroidism.

Thyroid antibody is also known as Thyroid Microsomal Antibody or Thyroid Peroxidase Antibody. Another antibody that is frequently tested along with the thyroid antibody test is the Thyroglobulin Antibody. Up to 10-15% of normal people can have a positive thyroid antibody test, even in the absence of any thyroid condition. The results are interpreted depending on why the test has been requested. The thyroid antibody test is usually requested by your doctor when you have hypothyroidism.

Hypothyroidism is a condition where the thyroid gland produces less thyroid hormone than needed reflecting as high TSH levels in the blood reports. The normal TSH range is usually between 1-5 mlu/ml for most people.

A few decades ago, lack of iodine in the diet (a nutrient for the thyroid gland) was the commonest reason for having Hypothyroidism. Now, autoimmune thyroid disease characterised by a positive thyroid antibody test is the commonest cause of Hypothyroidism.

So, the thyroid antibody helps to confirm the reason for the Hypothyroidism. It is also done in some cases where the hypothyroidism is very mild to help predict whether the hypothyroidism can worsen in future and needs treatment or not.

  • Predict future worsening of borderline Hypothyroidism. 

Sometimes, the results of the thyroid function tests may be borderline (TSH between 5-10 miu/ml). It is difficult for the doctor to decide whether this person needs treatment for these borderline TSH results, especially if they do not have any symptoms. In some situations, the treatment can be started right away as the treatment benefits the person – 

  1. A lady who is pregnant or is planning a pregnancy soon.
  2. A person has a swollen/enlarged thyroid gland.
  3. The person has close family members who already have a thyroid condition. 
  4. If the person suffers from high blood pressure or a heart disease

 In the absence of these above-listed conditions, the thyroid antibody test helps to understand whether these borderline TSH levels are likely to increase in future. A positive thyroid antibody test result signifies that this person has a greater chance of increasing TSH levels in the next few years, and it may be more prudent to start them on medication for thyroid. 

In people who have access to healthcare and can regularly test their TSH levels, treatment can be postponed until the TSH increases (this may not happen for several years).

In persons who cannot test their TSH levels regularly, treatment may be offered after an explanation of the consequences of untreated hypothyroidism if it occurs (Hypothyroidism symptoms: weight gain, swelling over face or feet, constipation, hair fall, dry skin, difficulty in getting pregnant, irregular periods).

Different laboratories may have different normal ranges for the thyroid antibody test /thyroid peroxidase antibody because there are several different processes by which the thyroid antibody can be tested. Any value above the upper limit of normal is considered positive (the upper limit is the higher number in the bracket at the right side of the test result). 

The thyroid antibody test report is an “all or none phenomenon”. Exceedingly high levels do not mean that the problem is more serious and is not a cause for alarm. If you already have hypothyroidism and are being treated for it, the thyroid antibody being positive merely confirms that you need treatment on an ongoing basis. 

There will be no change in the type of medicine you are taking and the medication dose. The thyroid antibody test does not have an impact on your hypothyroidism symptoms.

Thyroid antibody levels above the upper limit of normal for that laboratory means the test is positive; higher numbers are not a cause of concern.

As I explained, a positive thyroid antibody test means that you are experiencing an autoimmune thyroid condition. Now, this is not something to fear though the term sounds very ominous. 

The term “immunity” means the soldiers (tiny little cells) guard our body against any kind of infection like viruses and bacteria. Sometimes, our soldiers become misdirected and injure our own body – in this case, the thyroid gland. The attack of the thyroid gland by the immune cells leads to damage to the thyroid gland. During this attack, thyroid antibodies are generated; this means that a positive thyroid antibody test serves as a sign or a clue that the thyroid gland had experienced some damage in the past (almost like a scar that reminds us of a past injury).

A positive Thyroid Antibody test means that the Thyroid has sustained an attack by immune cells in our body.

The normal function of the thyroid gland is to make thyroid hormones (T3 / T4 in your blood report) which help keep our body in good health (sleep/weight/energy levels). After an attack on the thyroid gland, either the thyroid gland recovers and can function well, producing enough thyroid hormone for the body’s needs (characterised by normal TSH values).  Sometimes, the gland does not fully recover from the immune attack and thyroid hormone production is less than normal (characterised by high TSH called Hypothyroidism).

  • A positive thyroid antibody with normal TSH means an injured thyroid gland that has recovered fully.
  • A negative antibody test with raised TSH means an injured gland that could not recover fully.

As discussed in the previous section, for people with raised TSH levels above normal (usually > 10), treatment may be started right away. However, in people with borderline TSH values (between 5-10), a positive thyroid antibody may help predict the future likelihood of rising TSH levels and, thus, the need for treatment

E.g., TSH level 5.5 and negative Thyroid Antibody – may wait to start treatment.

TSH 5.5 and strongly positive Thyroid Antibody test – start treatment.

Several times I have seen patients repeatedly do their thyroid antibody tests/thyroid peroxidase test. This is not needed, and a single test is usually enough to decide whether the levels are elevated or not (remember the thyroid antibody is proof of past thyroid damage). Comparing values between reports also do not serve any purpose, and small increases/decreases can be ignored. 

The thyroid antibody test being positive do not lead to any symptoms. There is nothing you can do to lower thyroid antibody levels as they are not affected by external factors like lifestyle or diet, or exercise. We also do not recommend any medications like steroids to lower the antibody levels. Medications given for hypothyroidism do not impact antibody levels, only the TSH values.

The attempts to lower Thyroid Antibody Levels or to get rid of them stem from the mistaken belief that these antibodies are harmful to our body or that this would reduce the need for thyroid treatment. However, as discussed in the previous sections, the thyroid antibody signifies a past injury to the thyroid gland. It does not have any direct bearing on the thyroid gland function in the present. Thus, in the absence of evidence of direct harm by thyroid antibody or any impact on the dose of thyroid medications, lowering levels or getting rid of thyroid antibody serves no useful purpose.

So, yoga or diet modifications like avoiding cabbage/cauliflower or special exercises do not impact the thyroid antibody levels.

There are several reasons why a Thyroid Antibody Test is important in pregnancy. The interpretation of TSH levels is different than those for non-pregnant individuals. 


Scientific studies show that a TSH value of less than 2.5 is linked with the best results of pregnancy for both the mother and the baby. A positive Thyroid Antibody Test helps to decide whether very mild increases in TSH between 2.5 – 4.0 will benefit from treatment with thyroid medications.

Interpretation of Anti-body TSH Results | Dr Tejal Lathia


Thyroid Antibodies and Miscarriages

There are exceptions to these rules, however. In women who have had repeated pregnancy losses (miscarriages) or are having difficulty getting pregnant (undergoing fertility procedures like IUI or IVF), the benefits of thyroid medications outweigh the possible risks of overtreatment. There is some scientific evidence that points to thyroid antibody status being related with pregnancy losses (miscarriage). Please discuss with your Endocrinologist if you are undergoing fertility treatment, whether you will benefit from thyroid treatment.

Hypothyroidism is an autoimmune condition characterised by high/positive thyroid antibody levels. They have a slightly higher risk of having other coexisting autoimmune conditions like 

  1. Type 1 Diabetes (Insulin-Dependent Diabetes)
  2. Megaloblastic anaemia (Vit B12 and haemoglobin low)
  3. Addison’s Disease (Low Cortisol Levels)
  4. Vitiligo (white patches on the skin)
  5. Rheumatoid Arthritis (small joint pain/swelling)

Also, people with the above-listed conditions have a greater likelihood of developing Hypothyroidism with positive Thyroid Antibody Levels.

There is no direct relation between thyroid antibody test and cancer of any kind, even thyroid cancer. A thyroid antibody test DOES NOT help in the diagnosis of cancer. 

However, thyroid antibody testing is done in people with treated thyroid cancer. In people who have had thyroid cancer, the entire thyroid gland is removed. In these people, thyroglobulin antibody testing is done at regular intervals as rising thyroglobulin antibody levels may indicate a recurrence of cancer and result in a change of treatment.


Thyroid Antibody/Thyroid Peroxidase Antibody being positive is not a cause for fear. This test helps identify the cause of Hypothyroidism. It also aids in decision making about the need for treatment in people with borderline TSH levels. These antibodies are not harmful to our body and do not by themselves cause any symptoms. Repeated testing of antibody status is also not required. Meet your Endocrinologist for appropriate guidance about Thyroid Antibody.