Thyroid Peroxidase Antibodies (TPOAb)

TPO antibodies are the hallmark of autoimmune thyroid disease, characterized by chronic inflammation in the thyroid gland. Autoimmune thyroid disease can affect pregnancy, and understanding testing is essential in maternity care. This article will discuss thyroid peroxidase enzymes, autoimmune disease causes, and pregnancy-specific research. 

TPOAb Testing

The thyroid peroxidase antibodies (TPOAb) test measures the presence of antibodies against the thyroid peroxidase enzyme. 

Thyroid peroxidase catalyzes the iodination of tyrosine residues within thyroglobulin. This iodination occurs in the colloid of thyroid follicles. Coupling of the iodinated residues leads to the formation of thyroxine (T4) and triiodothyronine (T3). 

TPO antibodies attack and destroy the TPO enzymes. They are the hallmark of autoimmune thyroid disease, which is characterized by chronic inflammation in the thyroid gland. In Hashimoto’s thyroiditis, the immune system mistakenly targets and attacks the thyroid gland. TPO antibodies can also be found in Graves’ disease, which is characterized by hyperthyroidism.

​TPOAb in Pregnancy

​Any elevation in TPOAb should be monitored throughout pregnancy. It is not uncommon for TPO antibodies to increase in the first trimester if present preconception. For some, with the change in lymphocyte production and function and globulin production changes, there can be a drop in TPO enzymes in the late first trimester through the remainder of pregnancy. 

​TPO antibodies have been associated with an increased risk of thyroid dysfunction during pregnancy and postpartum, regardless of preconception thyroid-stimulating hormone (TSH) levels. 

High TPOAb in Pregnancy

Studies have shown that thyroid autoantibodies, especially TPOAb, can lead to adverse obstetric outcomes such as miscarriage and preterm delivery, even when thyroid function is normal.

​TPO antibodies >35 IU/mL are associated with an increased risk of pregnancy complications. The risk increases with increasing antibody levels.

Most Common Causes of High ​TPOAb in Pregnancy

• Environmental Chemical Exposure 
• Heavy Metal Exposure
• Mycotoxin Exposure
• Iodine Overdose
• Latent Viral Infections
• Lyme Disease
• Dysbiosis
• Gastrointestinal Pathogens (Parasites, Bacteria, etc...)
• Chronic Infections
• High Dose Biotin Supplements
• Certain Medications (Accutane, Interferon) 
• Nutritional Deficiencies (vitamin D, magnesium, selenium)

Low TPOAb in Pregnancy

​Not considered pathogenic

Confused About Thyroid Testing in Pregnancy?

We cover this and more in my Advanced Maternal Blood Work Analysis Course - MEAC Approved

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Medical Disclaimer:
This content is for educational purposes only and is intended for licensed medical professionals. It is based on current research, subject to change, and not intended to diagnose, treat, or prevent any medical condition. This information does not replace consultation with a qualified healthcare provider. Seek professional medical evaluation and treatment from a licensed provider. Use of this information is at your own risk.​

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