What Are Thyroid Antibodies?

An estimated 20 million Americans have some form of thyroid disease, but up to 60% of those who do are unaware of their condition (14). Optimal thyroid function is important for physiological functioning and overall health. In the United States, autoimmunity is the most common cause of thyroid disease; however, conventional diagnostic algorithms do not recommend routine ordering of autoimmune testing as part of the workup for thyroid disorders (9). Lab tests measuring thyroid antibodies can help distinguish autoimmune thyroid disease (AITD) from other thyroid conditions. This article will discuss the importance of thyroid antibodies, interpreting test results, and general guidelines for managing AITD.

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Basics of The Thyroid Gland

The thyroid gland, a small butterfly-shaped endocrine organ located in the neck, plays a crucial role in maintaining the body's overall health. Its primary function revolves around producing and regulating hormones that influence various bodily functions. Two key hormones, thyroxine (T4) and triiodothyronine (T3), are synthesized by the thyroid gland and are responsible for controlling metabolism, energy production, and overall growth and development. (19)

When the thyroid gland functions optimally, it produces an appropriate amount of hormones, ensuring the smooth operation of the body's biological processes. This is called a euthyroid state. However, disruptions in the thyroid's activity can lead to a range of disorders, commonly referred to as thyroid dysfunction. (19) 

Hypothyroidism affects up to 5% of the general population. In a hypothyroid state, the thyroid produces insufficient hormones, which may result in symptoms due to a sluggish metabolism. (19) 

On the flip side, hyperthyroidism occurs when the thyroid is overactive, leading to an excess of hormones. It is less common than hypothyroidism, affecting 1% of Americans. This can manifest as symptoms like weight loss, rapid heartbeat, and heightened anxiety. (19)

Autoimmune disorders, such as Hashimoto's thyroiditis and Graves' disease, contribute significantly to thyroid dysfunction. In Hashimoto's thyroiditis, the immune system mistakenly attacks the thyroid, causing inflammation and impairing its ability to produce hormones. Graves' disease, on the other hand, prompts the thyroid to overproduce hormones due to autoimmune stimulation, leading to hyperthyroidism.

What Are Thyroid Antibodies?

Antibodies are proteins produced by the immune system's B cells in response to foreign proteins called antigens. Under normal circumstances, they help protect us from pathogenic invaders, like viruses and bacteria, to prevent illness. However, in some instances, the immune system will mistakenly produce antibodies to self-proteins, signaling the immune system to attack its own cells, tissues, and organs. Thyroid antibodies are produced when the immune system initiates attacks on specific proteins and tissues related to the thyroid gland, leading to thyroid inflammation, tissue damage, and disruptions in healthy thyroid function. The presence of thyroid antibodies in a euthyroid state may increase the risk of future thyroid disease. The presence of thyroid antibodies in hypo- and hyperthyroid states is used to identify AITD. (23) 

There are several types of thyroid antibodies, each with a distinct function and impact on thyroid health:

Thyroid Peroxidase (TPO) Antibodies 

TPO antibodies target an enzyme called thyroid peroxidase. Thyroid peroxidase plays a crucial role in the synthesis of thyroid hormones. Over 90% of individuals diagnosed with Hashimoto's thyroiditis test positive for these antibodies. It's worth noting that while TPO antibodies are strongly associated with Hashimoto's, they can also be found in other thyroid conditions, including 70% of Graves' disease cases. (23) 

Thyroglobulin (TG) Antibodies  

TG antibodies target thyroglobulin, a protein involved in synthesizing, storing, and releasing thyroid hormones. TG antibodies are detected in patients less frequently than TPO antibodies. While TG antibodies are mainly used to confirm the diagnosis of Hashimoto's, they may be present in other thyroid states. TG antibodies have a 20-90% prevalence in Hashimoto's thyroiditis, 30-60% in Graves' disease, and 10-27% in healthy adults. (21, 23) 

Thyroid Stimulating Hormone Receptor Antibodies (TRAb)

TRAbs mimic thyroid stimulating hormone (TSH), a hormone secreted by the pituitary to signal the thyroid to produce thyroid hormones. 95% of patients with Graves' disease will have elevated TRAb. (23) 

Testing for Thyroid Antibodies

Testing for thyroid antibodies is an important aspect of identifying AITD. The different thyroid antibodies can be measured as part of a comprehensive thyroid panel. Including these tests in a laboratory evaluation helps to identify autoimmunity as a potential underlying cause of thyroid dysfunction. 

TPO antibodies, TG antibodies, and TRAb can be ordered through standard labs to detect and quantify each of these antibodies in circulation. One method commonly used to measure TRAb is the thyroid-stimulating immunoglobulin (TSI) assay. (15, 19) 

These tests are recommended based on specific symptoms and clinical indications. The following signs and symptoms can indicate hypothyroidism, warranting the need to order TPO and TG antibodies: 

• Unintentional weight gain
• Depression
• Dry skin, brittle nails, and hair loss
• Loss of the outer third of the eyebrow
• Fatigue and brain fog
• Cold intolerance
• Joint pain and muscle cramping
• Heavy periods
• Constipation

The following signs and symptoms can indicate hyperthyroidism, warranting the need to order all three thyroid antibody tests:

• Unintentional weight loss
• Anxiety and irritability
• Rapid heart rate and heart palpitations
• Tremor
• Sweating and increased body temperature
• Muscle spasms and weakness
• Diarrhea
• Insomnia

Additionally, individuals with a family history of thyroid disorders or those with existing autoimmune diseases are considered high-risk groups, justifying regular testing to detect potential issues early on. (22)

Once a patient has been identified with AITD, functional and integrative medical doctors may perform serial monitoring of thyroid antibodies, along with other thyroid hormones, to observe autoimmune disease progression and treatment efficacy. 

Interpreting Thyroid Antibody Test Results

It's important to note that thyroid antibody tests should be interpreted in conjunction with other thyroid function tests, such as TSH, free T3, and free T4. In healthy individuals, thyroid antibodies are usually very low or indetectable; normal reference ranges may vary slightly between different laboratories. 

Elevations in any of the thyroid antibodies indicate an active autoimmune response against the thyroid. The severity of elevation may correlate to the degree of ongoing autoimmune activity. A positive result does not always mean that you have a thyroid condition or need active treatment for your thyroid; however, it may mean that you have a higher risk of developing future thyroid disease. (2)

Elevations in TPO antibodies may be due to subacute thyroiditis, Hashimoto's thyroiditis, or Graves' disease. High levels have also been measured in patients with other autoimmune diseases, including autoimmune hemolytic anemia, autoimmune hepatitis, autoimmune adrenal disease, rheumatoid arthritis, Sjogren's syndrome, and systemic lupus erythematosus. Elevated TPO antibodies have also been linked to an increased risk of miscarriage, preeclampsia, premature birth, and in vitro fertilization failure. (2)

Elevated TG antibodies have been measured in patients with subacute thyroiditis, Hashimoto's thyroiditis, Graves' disease, systemic lupus erythematosus, and type 1 diabetes. (1) 

High levels of TSI in the blood support the identification of Graves' disease (24).

Functional Medicine Approach to Thyroid Antibodies

Functional medicine doctors commonly order thyroid antibodies during the initial identification of thyroid disease because it helps differentiate the underlying cause of thyroid dysfunction. Once it has been determined that autoimmunity is the underlying cause of an under- or overactive thyroid, functional medicine offers a unique perspective to addressing autoimmunity by considering a wide range of factors that may contribute to the immune system's attack on the thyroid gland. Functional medicine is patient-centered and focuses on individualized plans. Instead of applying a one-size-fits-all approach, practitioners work to understand the unique factors contributing to each patient's condition. In addition to prescribing hormone replacement therapy (for hypothyroidism) or antithyroid medications (for hyperthyroidism), this may involve a combination of lifestyle modifications, dietary changes, supplementation, and stress management strategies. (20) 

The quantitative measurement of thyroid antibodies helps determine the magnitude of immune system imbalance and autoimmunity. Functional medicine emphasizes the importance of maintaining a balanced and healthy immune system. Factors such as gut health, nutritional status, and chronic inflammation are carefully evaluated to identify potential triggers contributing to a dysregulated immune system. (12) 

The gut's health plays a critical role in the development and progression of autoimmunity. Leaky gut syndrome, where the intestinal lining becomes more permeable, is believed to contribute to autoimmune conditions. Functional medicine practitioners often explore and address gut issues as part of the overall strategy for managing thyroid disorders.

Functional medicine strongly emphasizes assessing and correcting nutrient deficiencies that can impact thyroid health. Nutrients such as vitamin A, zinc, selenium, iodine, vitamin D, and omega-3 fatty acids are essential for maintaining a healthy thyroid function and modulating the immune response.

Chronic stress and adrenal dysfunction are also factors that functional medicine takes into account. Prolonged stress may contribute to the dysregulation of the immune system and exacerbate autoimmune responses. Functional medicine practitioners often address stress management and adrenal health as part of a comprehensive approach to thyroid disorders.

Living with Thyroid Antibodies

Living with AITD requires a proactive approach to long-term management, consistent monitoring, and considerations for maintaining a good quality of life. Thyroid conditions may require ongoing management, but individuals can lead fulfilling and healthy lives with consistent care and lifestyle adjustments. Here are some valuable pieces of advice for individuals navigating life with thyroid antibodies:

Schedule regular check-ups with your healthcare provider to monitor thyroid function, antibody levels, and overall health. This allows for routine monitoring of thyroid markers, early detection of any changes in thyroid/immune function, and necessary adjustments to your plan.

If you are prescribed medication for thyroid disorders, such as levothyroxine for hypothyroidism or antithyroid medications for hyperthyroidism, adhere to your prescribed regimen consistently. 

Adopt a nutrient-dense, anti-inflammatory diet that supports thyroid health. Patients may also benefit from eliminating gluten-containing foods from the diet. Consult with a functional nutritionist or dietician for personalized dietary recommendations. (7, 8)

Prioritize stress management techniques, as stress can exacerbate thyroid conditions. Incorporate relaxation methods such as meditation, deep breathing, yoga, or hobbies that bring joy and relaxation. (9) 

Prioritize good sleep hygiene to ensure adequate and restful sleep. Sleep is crucial for hormone regulation, stress management, and overall health. Establish a consistent sleep routine and create a comfortable sleep environment. (5) 

Consider seeking support for emotional well-being. Living with a chronic condition can be challenging, and counseling or support groups may provide valuable resources for coping with the emotional aspects of thyroid disorders. (11) 

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Key Takeaways to Remember About Thyroid Antibodies

Prioritizing thyroid health involves recognizing the critical role of understanding thyroid antibodies for effective management. These antibodies are key indicators of autoimmune thyroid disorders like Hashimoto's or Graves' disease. Proactive health management is essential for those with thyroid conditions. Monitoring antibody levels alongside thyroid function tests allows for early detection and adjustments to plans, optimizing long-term well-being. By staying informed, adhering to prescribed regimens, and actively participating in healthcare decisions, individuals can empower themselves to navigate the complexities of thyroid health and enhance their overall quality of life.