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Hashimoto's Disease and TPO Antibodies

Learn about Hashimoto's thyroiditis, the role of TPO antibodies, and how this condition relates to hypothyroidism.
Hashimoto's Disease and TPO Antibodies
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As part of the endocrine system, your thyroid gland produces hormones that regulate your body’s energy use and many other essential bodily functions. When your thyroid hormone production drops, your body processes slow down, affecting every organ, gland, tissue, and cell.

While there are many causes of an underactive thyroid, we will focus on one: Hashimoto’s thyroiditis, an autoimmune disease. Ahead, learn more about Hashimoto’s thyroiditis and the role of thyroid peroxidase (TPO) antibodies.

Hashimoto’s thyroiditis: the basics

Hashimoto’s thyroiditis is an autoimmune disorder resulting in chronic thyroid gland inflammation. Hashimoto’s is characterized by the immune system mistakenly attacking healthy thyroid tissue. As a result of the damage, thyroid hormone production drops. Without enough thyroid hormone for your body to function correctly, you develop a medical condition called hypothyroidism.

The difference between Hashimoto’s and hypothyroidism

Hypothyroidism is an underactive thyroid condition, whereas Hashimoto’s is an autoimmune disease that can cause hypothyroidism.

Essentially, hypothyroidism is a problem with your thyroid gland. Hashimoto’s is a problem with your immune system. You can have one without the other. Yet, they commonly go hand-in-hand.

Hashimoto’s is the leading cause of hypothyroidism in the United States, affecting roughly 5% of the population. Because Hashimoto’s results in hypothyroidism, both conditions share the same symptoms, such as:

  • Tiredness and fatigue
  • Weight gain
  • Trouble tolerating cold
  • Joint and muscle pain
  • Constipation
  • Dry, thinning hair
  • Heavy or irregular menstrual periods
  • Infertility
  • Feelings of depression
  • Memory problems

Causes of Hashimoto’s thyroiditis

Experts are still determining why the immune system, which is supposed to defend the body from harmful viruses and bacteria, sometimes turns against the body’s healthy tissues and organs.

Some experts think a virus or bacterium might trigger the response, while others believe it may involve a genetic characteristic. An estimated 70%–80% of those with an autoimmune thyroid disorder either have a family history of a thyroid disorder or a personal history of another autoimmune disorder such as celiac disease or rheumatoid arthritis.

Despite the strong genetic link, it’s likely that a combination of factors—including environmental (stress, diet, toxins), sex, and age—determine your likelihood of developing Hashimoto’s thyroiditis.

Hashimoto’s thyroiditis is progressive

You might not notice signs or symptoms of Hashimoto’s disease at first, or you may see swelling at the front of your throat (goiter). Hashimoto’s disease often progresses slowly. Over time, it causes chronic thyroid damage, leading to a drop in thyroid hormone levels in your blood.

In the early stages, the body compensates and produces more thyroid hormone to keep your levels within “normal” ranges. At this point, your thyroid is still close to fully functional. While TPO antibodies may be present in the blood, it can take several years before hypothyroid symptoms appear.

As TPO antibodies destroy more thyroid tissue, the thyroid gland loses the ability to compensate. You begin to become deficient in thyroid hormone and may start to feel hypothyroid symptoms.

Eventually, the gland completely loses its ability to produce thyroid hormone, considered the end-stage of Hashimoto’s thyroiditis.

What are TPO antibodies?

Thyroid peroxidase (TPO) is an enzyme in the thyroid gland that plays a vital role in producing thyroid hormones. TPO converts iodide ions absorbed from food into an active form of iodine to be used by the body. The body needs iodine to make the thyroid hormones thyroxine (T4) and triiodothyronine (T3).

Antibodies are proteins the body produces to protect against foreign invaders such as germs. But, sometimes, the body develops antibodies against healthy cells. In general, an elevated antibody level in the blood suggests that your immune system is attacking normal, healthy tissue. This results in either destruction of the healthy cells or, in some cases, activates excessive hormone secretion.

Since TPO is mainly in your thyroid cells, TPO antibodies may be a sign of autoimmune thyroid disorder. There are two autoimmune thyroid disorders. One we have already discussed is Hashimoto’s thyroiditis. The second is Grave’s disease, which results in an overactive thyroid (hyperthyroidism). TPO antibodies are present in both thyroid autoimmune disorders; however, symptoms of these two thyroid autoimmune disorders differ.

How is Hashimoto’s thyroiditis diagnosed?

The diagnosis of Hashimoto’s thyroiditis comes from laboratory testing and physical examination. Your complete thyroid blood panel should include thyroid-stimulating hormone (TSH), free triiodothyronine (fT3), free thyroxine (fT4), and TPO antibodies. All this information helps determine your thyroid function and the cause of your over- or underactive thyroid.

What does a “positive” result for TPO antibodies mean?

Lab results will read as “positive” or “negative” on whether you have TPO antibodies in your blood sample.

Suppose you show a negative result for TPO antibodies. In this case, TPO antibodies weren’t discovered in your blood. Thus, if you have symptoms of a thyroid condition, it is unlikely -- but not impossible -- that autoimmune thyroiditis is the cause.

Now, suppose you show a positive result for TPO antibodies. In that case, it may mean you have an autoimmune thyroid disorder such as Hashimoto’s or Grave’s disease.

What is most commonly found in blood work that indicates Hashimoto’s is elevated TSH and low T4 (thyroxine) in conjunction with elevated TPO antibodies. Besides a positive TPO antibody level, those with Hashimoto’s will also frequently test positive for high levels of thyroglobulin (Tg) -- a protein produced by the thyroid.

Can I have thyroid antibodies without hypothyroidism?

The short answer is “yes.”

In many cases, thyroid antibodies can be the first sign of a thyroid problem. The presence of thyroid antibodies in the blood does not necessarily mean a person has overt hypothyroidism. But, it does mean there is an ongoing attack against the thyroid. This attack increases your risk for future thyroid disorders.

I have positive TPO antibodies; now what?

Individuals with elevated TPO antibodies but normal thyroid function tests (TSH and free T4) do not necessarily need treatment. Similarly, those with only slightly elevated TSH (subclinical hypothyroidism) may not need thyroid hormone medication. In these cases, individuals should have repeat testing after 3 to 6 months to check their thyroid status.

Overt hypothyroidism (high TSH and low thyroid hormone levels) is managed by replacing the amount of thyroid hormone that your thyroid gland can no longer make with thyroid hormone replacement medication. Hypothyroidism is not curable, but you can take medication to restore your TSH and thyroid hormone levels.

Most patients with hypothyroidism will require lifelong treatment with thyroid hormone replacement medication. Finding the appropriate dose may require trial and error, particularly at the beginning. Thyroid levels should be tested every 6 to 8 weeks after any dose change until achieving the correct dose. After that, testing thyroid function once a year is generally enough.

Ways to lower TPO antibody levels

Remember:  the presence of TPO antibodies doesn’t mean you have hypothyroidism. But, they do put you at a greater risk of developing hypothyroidism in the future. And while you can’t reverse an autoimmune disorder, you can stall its progression and sometimes even achieve remission.

Lowering the level of TPO antibodies can help protect your thyroid gland. A healthy diet and exercise routine can help limit the disease’s progression. Here are six other ways to lower your TPO antibody levels:

A note from Paloma Health

Knowing how well your thyroid functions is the first step to improving your thyroid health and well-being. Most of the time, this involves visiting your local lab to have your thyroid blood panel drawn. And, if you take certain supplements like biotin, you may need to hold them a couple of days in advance to get accurate results.

But, at-home thyroid testing allows you to skip the lab visit. Paloma’s at-home testing kit will enable you to quickly and easily test your thyroid function from the comfort of your home. Our full thyroid panel includes TSH, free T4 and T3, and TPO antibodies. (You don’t have to stop biotin supplements in advance to get accurate results!)

We also recommend you work with a trustworthy thyroid doctor to find the optimal functioning of your thyroid. Schedule a free consultation with a care advisor to determine if Paloma Health might be the right fit for you.

The above information is not a diagnosis, treatment, or cure for thyroid disease. We recommend that you work with your Paloma Healthcare team to learn how to optimize your thyroid health.

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Emilie White, PharmD

Clinical Pharmacist and Medical Blogger

Emilie White, PharmD is a clinical pharmacist with over a decade of providing direct patient care to those hospitalized. She received her Doctor of Pharmacy degree from Massachusetts College of Pharmacy and Health Sciences. After graduation, Emilie completed a postgraduate pharmacy residency at Bon Secours Memorial Regional Medical Center in Virginia. Her background includes caring for critical care, internal medicine, and surgical patients.

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