What does an elevated Thyroid Peroxidase (TPO) antibody and thyroid antibody indicate?

From the Guidelines

Elevated TPO and thyroid antibodies are indicative of autoimmune thyroid disease, most commonly Hashimoto's thyroiditis, which can lead to hypothyroidism and requires regular monitoring and potentially levothyroxine replacement therapy. This condition occurs when your immune system mistakenly attacks your thyroid gland, gradually leading to inflammation and potentially decreased thyroid function 1. The presence of thyroid autoantibodies, such as antithyroid peroxidase (TPO) and antithyroglobulin (TG), identifies patients at increased risk for thyroid autoimmunity 1. Some key points to consider include:

• Regular monitoring of thyroid function tests (TSH, free T4) every 6-12 months is recommended, even if your thyroid function is currently normal, as many people with positive antibodies eventually develop hypothyroidism 1.
• If hypothyroidism develops, levothyroxine replacement therapy (typically starting at 25-50 mcg daily, adjusted based on TSH levels) is prescribed 1.
• The presence of these antibodies explains symptoms like fatigue, weight gain, cold intolerance, and dry skin that may occur as thyroid function declines.
• Autoimmune thyroid disease has a genetic component and is more common in women, with risk increasing with age.
• Selenium supplementation (200 mcg daily) may help reduce antibody levels in some patients, though evidence for this remains limited. It is essential to note that the presence of anti-TPO antibodies predicts a higher risk of developing overt hypothyroidism (4.3% per year vs 2.6% per year in antibody-negative individuals) 1.

From the Research

Elevated TPO and Thyroid Antibody Indications

• An elevated TPO (thyroid peroxidase) and thyroid antibody level can indicate the presence of an autoimmune thyroid disease, such as Hashimoto's thyroiditis or Graves' disease 2, 3, 4.
• Hashimoto's thyroiditis is a common autoimmune disorder that affects the thyroid gland, leading to hypothyroidism, and is characterized by the presence of TPO antibodies 4.
• Elevated TPO antibodies can also be associated with an increased risk of recurrent miscarriages and preterm birth in pregnant women 4.
• The presence of thyroid antibodies, including TPO antibodies, can be an indicator of autoimmune thyroid disease, but it is not a definitive diagnosis, and further testing and evaluation are necessary to confirm the diagnosis 5, 6.

Clinical Presentation and Diagnosis

• The clinical presentation of Hashimoto's thyroiditis can vary, but common symptoms include thyrotoxicosis, euthyroidism, and hypothyroidism 4.
• The diagnosis of Hashimoto's thyroiditis is typically made based on the presence of TPO antibodies, thyroid ultrasound, and thyroid function tests 3, 4.
• The management of Hashimoto's thyroiditis typically involves thyroid hormone replacement therapy, and the dose of levothyroxine (LT4) used for treatment is based on the degree of preserved thyroid functionality and lean body mass 4.

Association with Other Autoimmune Diseases

• Individuals with one autoimmune disease, such as Hashimoto's thyroiditis, are at risk of developing a second autoimmune disease 5.
• The presence of TPO antibodies can be an indicator of an increased risk of developing other autoimmune diseases, such as systemic autoimmune diseases 5.
• However, the presence of thyroid antibodies, including TPO antibodies, is not a definitive indicator of autoimmune encephalopathy, and further testing and evaluation are necessary to confirm the diagnosis 6.