3 Common Tests For Thyroid Peroxidase Antibodies

By Corri Peterson

If you are being tested for thyroid peroxidase antibodies, there is a reason your doctor believes you may have an autoimmune thyroid disease.

Thyroid peroxidase antibodies’ presence indicates that the cause of thyroid disease is an autoimmune disorder, such as Hashimoto’s disease or Graves’ disease. With these autoimmune disorders, your immune system makes antibodies that attack the normal thyroid tissue, causing swelling and tenderness and leading to increased or reduced thyroid function. (If you purchase through the links in this post, we may receive a commission.)

Thyroid peroxidase (TPO) is an enzyme typically found in the thyroid gland. TPO plays an essential role in producing thyroid hormones. A TPO test detects antibodies against TPO in the blood. If you have a thyroid disease diagnosis, your doctor may suggest a TPO antibody test and additional thyroid tests to help find the cause.

How Do They Test For Thyroid Peroxidase Antibodies

Thyroid Peroxidase Antibodies

After a physical exam, blood samples are drawn to test the levels of thyroid-stimulating hormones and the levels of thyroid peroxidase antibodies.

Here are the reference ranges for the three antithyroid antibodies:

  • Thyroid peroxidase antibodies (TPOAb): Less than 35 IU/mL.
  • Thyroglobulin antibodies (TgAb): Less than 20 IU/mL.
  • Thyroid-stimulating immunoglobulin antibodies (TSI): Less than 140% of basal activity

Here are the reference ranges for thyroid hormones:

TSH (Thyroid Stimulating Hormone): Reference range- 0.5-4.70 mIU/L

Some labs have upper limits of 8-10 mIU/L, while others have upper limits of 5.0 mIU/L. Many functional medicine and holistic doctors use upper limits of 2.5 mIU/L.

T4 (Thyroxine): Reference range: 4.5-12.5ug/dl

FT4 Free t4-(free thyroxine): Reference range: 0.8-1.8ng/dl

T3 (Triiodothyronine): Reference range: 87-180 ng/dl

FT3 (Free T3): Reference range-230-420pg/dl

RT3-(reverse T3/reverse triiodothyronine)– Reference range-10-24 ng/dl

Free T3/reverse T3 ratio– A ratio of 2 or higher

Your doctor may request a Radioactive iodine uptake test to measure the rate the thyroid absorbs iodine. This test reveals if the thyroid is overactive or underactive.

Your doctor may also request imaging tests such as an ultrasound, CT scan, or magnetic resonance imagery (MRI).

The Autoimmune Thyroid Diseases

Graves’ Disease

Graves’ disease creates an overactive thyroid that makes more thyroid hormone than the body needs, known as hyperthyroidism. In addition, Graves’ disease causes your immune system to produce antibodies known as thyroid-stimulating immunoglobulins. These antibodies attach to healthy thyroid cells causing your thyroid to create too much thyroid hormone.

These symptoms are more specific to Graves’ disease:

Feeling tired

Fast or irregular heartbeat

Irritability and anxiety

Frequent bowel movements

Trouble sleeping

Weight loss

Sensitivity to heat

Risk Factors of Developing Graves’ Disease

Thyroid Peroxidase Antibodies

Family History- Having a family member with Graves’ disease increases your risk

Sex- Women are more likely to develop Graves’ disease

Age- Graves’ disease usually develops before the age of 40

Pregnancy- Being pregnant or childbirth may trigger Graves’ disease, especially if there’s a family history

Physical or Emotional Stress- Illness or stress may trigger Graves’ disease, again, if there’s a family history

Other autoimmune disorders- If you have one autoimmune disease, you are at risk to develop another. Diabetes or rheumatoid arthritis are examples.

Smoking- Cigarette smoking increases the risk of Graves’ by lowering your immune system. Smokers with Graves’ disease also have an increased risk of Graves’ ophthalmopathy.

Treatment Options for Graves’ Disease

Radioactive iodine-

The most common treatment for Graves’ disease is radioactive iodine (RAI) or radioiodine. This treatment destroys overactive thyroid cells and is given in liquid or in a capsule.

There are concerns that radioiodine may put you at a higher risk for Thyroid Eye Disease. Consult with your health care provider if you feel at risk.

Antithyroid Medicines-

Antithyroid medicines reduce the amount of thyroid hormone your body produces, however, lasting results depend on treating the actual autoimmune disease and slowing the production of thyroid peroxidase antibodies.


The least common form of treatment for Graves’ disease is a Thyroidectomy, the complete or partial removal of the thyroid gland. This is for those with extremely enlarged thyroids or goiter and pregnant women who can’t tolerate antithyroid drugs.

Those patients who have had radioactive iodine or surgery will have to take thyroid hormone for the rest of their lives.

While RAI is sometimes necessary, many people receive this treatment method when they could have restored their health through natural treatment methods. Functional medicine doctors will recommend adding selenium and a whole foods diet to slow the production of thyroid peroxidase antibodies.

FYI- Most conventional doctors will not give their patients any options other than RAI. They tell their patients that is the only treatment available and that Synthroid is the only replacement hormone that works!

There are many people who have received radioactive iodine therapy who are depressed and angry when they realize that they might have “saved” their thyroid gland instead of permanently damaging it.

They wonder if natural remedies would have corrected the disease without damaging or removing it.
Keep in mind that even if you have had RAI or surgery, following a natural thyroid healing program will help ease any remaining symptoms and help restore your health.

After all, damaging or removing your thyroid does nothing to address the autoimmune disease, but does leave you at risk of developing another autoimmune disease.

How to Know If Natural Thyroid Treatments Will Work

Thyroid Peroxidase Antibodies

Ultimately, the goal of natural thyroid treatment is not to manage symptoms but to get to the underlying cause of the disease. Natural treatment methods will often restore the individual’s health, eliminating the need for thyroid medication for the rest of their lives.

However, other times it’s not possible to completely restore their health. Still, it is possible to strengthen other areas of their body that led to their thyroid condition, which will help prevent future diseases from developing.

The reason is radioactive iodine therapy does nothing for the root cause of the thyroid condition. While it does help manage some of the symptoms, one needs to understand that the malfunctioning thyroid gland isn’t the cause of a hyperthyroid disorder in most cases. Destroying the gland makes absolutely no sense unless someone has severe symptoms and has tried every treatment method available.

However, the truth is that while RAI should be used as a last resort, you need to know that this is how most endocrinologists and other medical doctors are trained to treat such conditions.

While some great endocrinologists are out there, most are trained to use drugs and radioactive iodine therapy as their only treatment methods for hyperthyroid conditions. So, if you asked your endocrinologist or general practitioner about natural treatment methods, they would advise you not to follow such an unproven protocol.

Even if this isn’t the case, remember that what initially caused your thyroid condition to develop most likely still exists. Because of this, you should consider natural thyroid treatment methods to “optimize” your health and help prevent other autoimmune conditions from developing in the future.

Risk Factors for Hashimoto’s thyroiditis

While some scientists believe a virus or bacterium triggers the response, others feel it’s a genetic flaw, and a growing number believe environmental toxins are to blame.

These symptoms are more specific to Hashimoto thyroiditis:

Enlarged thyroid, also known as a goiter

Fatigue (tiredness) and sluggishness

Weight gain

Sensitivity to cold

Slowed heart rate

Memory problems


Pale, dry skin

Puffy face

Fullness in the throat

Untreated Hashimoto’s Can Cause Several Health Issues

Thyroid Peroxidase Antibodies

Here are five of the most common-

Hypothyroidism is a common cause of goiters. Your thyroid’s constant stimulation to release hormones can cause the gland to enlarge, known as a goiter. A large goiter affects your appearance and may interfere with swallowing or breathing.

Heart Problems

Hashimoto’s disease slows thyroid function, so heart rate is slower, blood pressure increases, fluid retention is more significant, and increased cholesterol levels. Severe hypothyroidism can lead to heart failure.

Mental health issues

Thyroid disorders often cause emotional or mental health symptoms along with physical symptoms. As a result, it’s common for people to see a doctor for symptoms they had no idea were linked to thyroid disease.

A few of the most common mental health symptoms-

ADHD Depression and anxiety

Difficulties with concentration

Short-term memory lapses

Lack of interest and mental alertness

Slowed mental functioningIrritability



It’s common for a person with symptoms of depression, anxiety, fatigue, insomnia, and “brain fog” to mistakenly receive a diagnosis of depression, anxiety, or bipolar disorder. As a result, they receive prescriptions for antidepressants, mood stabilizers, sedatives, or all three, instead of thyroid dysfunction treatment.

Myxedema (miks-uh-DEE-muh)

This life-threatening condition can develop due to deficient hormone levels caused by severely advanced hypothyroidism due to untreated Hashimoto’s disease. Symptoms include drowsiness, confusion, and hypothermia.

In addition, due to progressive thyroid disease, skin changes include swelling of the face, lips, eyelids, tongue, and thickening of the skin anywhere on the body, especially on the lower legs.

A life-threatening condition created by hypothyroidism is a myxedema coma, also known as a myxedema crisis. A more accurate term since a person experiencing a myxedema coma doesn’t always fall into a comatose state.

A myxedema coma can be triggered by colds, sedatives, infection, or other stress on your body. Myxedema coma requires immediate emergency medical treatment.

Higher Risk of Birth defects

Babies born to women with hypothyroidism due to Hashimoto’s disease or hyperthyroidism due to Graves’ disease may have a higher risk of congenital disabilities. Studies show that these children are more prone to intellectual and developmental problems.

In addition, there are links between hypothyroid pregnancies and birth defects, an increased risk of heart, brain, and kidney defects, and risk of premature birth, miscarriage, and stillbirth.

Because thyroid hormones are crucial to your baby’s brain and nervous system development, untreated hypothyroidism can cause problems with low IQ and normal development, especially during the first trimester.

If you’re planning to get pregnant or are in early pregnancy, be sure to have your thyroid level checked. This checkup is crucial there is a history of thyroid disease in your family.

Monitoring Your Thyroid During Pregnancy Helps Avoid Dangerous Health Issues:

Thyroid Peroxidase Antibodies

Preeclampsia- A severe high blood pressure condition in which organs like kidneys and liver are not working correctly. This pressure also stresses the heart and can cause pregnancy problems.

Pulmonary hypertension– This type of high blood pressure is in the lungs’ arteries and the right side of your heart.

Placental abruption– This is a condition where the placenta separates from the uterus wall before birth. The placenta delivers food and oxygen through the umbilical cord to the baby.

Heart failure– Your heart isn’t pumping as it should.

Thyroid storm– Your symptoms get much worse, suddenly. This rare, life-threatening condition puts pregnant women at high risk of heart failure.

Anemia– A lack of healthy red blood cells; they carry oxygen to every part of your body.

Gestational hypertension– This high blood pressure starts after 20 weeks of pregnancy and goes away after giving birth.

Myxedema– Severe, untreated hypothyroidism that may cause coma and death is a rare condition.

Postpartum hemorrhage-When a woman has heavy bleeding after delivery. The severe but rare condition usually happens one day after birth but is possible up to twelve weeks after the delivery.

Developing Fetuses Face Multiple Health Problems

Premature birth– Babies born before 37weeks of pregnancy are considered premature.

Goiter– When there is a lack of iodine, the thyroid gets larger, trying to capture all the iodine it can to make the right amount of thyroid hormone.

Low birthweight– A baby born weighing less than five pounds, 8 ounces.

Thyroid problems– Babies whose mothers have autoimmune thyroid disease risk developing thyroid problems because the antibodies can cross through the placenta.

Miscarriage or stillbirth– Rates for miscarriage are double in women with mild thyroid dysfunction. Simultaneously, stillbirth risk is seven times greater than women with normal thyroid hormone levels.

Infantile myxedema– Severe hypothyroidism can cause dwarfism and intellectual disabilities, leading to low intelligence and a lack of daily life skills.

Ongoing Problems with growth and brain and nervous system development– The nervous system helps you think, move, and feel. If left untreated, particularly in the first trimester, hypothyroidism can cause low IQ in a baby.

As you can see, if you suspect you have a thyroid problem or thyroid disease runs in your family, thyroid testing is vital for your health and the health of your developing baby. Remember, your body attacked your thyroid; your thyroid just responded. Many experts believe that the increase in thyroid disorders is a combination of stress, poor diet, and environmental toxins.

Lifestyle Changes Improve Thyroid Function

Holistic and functional medicine doctors recommend less processed food, avoiding toxins when possible (they are everywhere and in everything, so avoiding them is impossible), and reducing stress to ease any symptoms and improve your thyroid function. As I mentioned earlier, whole foods slow the production of thyroid peroxidase antibodies, making it easier for your thyroid to function properly.

I have written a post about how toxins affect your thyroid health. You can read it here: https://knowyourthyroid.com/improving-your-thyroid-gland-function-17-toxins-to-avoid/ Keep in mind: these toxins have a cumulative effect, even if you are getting a tiny amount of toxins from different sources, it adds up and your thyroid suffers.

You can improve your thyroid health and ease your symptoms with a few changes. It will be totally worth it!

Take care,



Leave a Reply

Your email address will not be published.