Thyroid Receptor Antibodies (TRAb)

Thyroid receptor antibody (TRAb) testing is a tool for monitoring thyroid function in pregnancy, especially in cases of autoimmune thyroid disorders like Graves’ disease. Elevated TRAb levels can affect maternal and fetal health, making early detection and management crucial. This article will discuss TRAb reference ranges, the implications of elevated levels, and how these antibodies influence pregnancy outcomes.

TRAb Testing

The thyroid receptor antibodies (TRAb) test measures the levels of antibodies that target the thyroid-stimulating hormone (TSH) receptor, also known as the thyrotropin receptor, on the surface of thyroid cells.

This test detects two main types of thyroid receptor antibodies.

Thyroid-Stimulating Immunoglobulin (TSI): TSI antibodies mimic the actions of TSH by binding to and stimulating that TSH receptor. Continuous stimulation causes a decrease in TSH and an increase in T4 and T3 indices, generally with an increase in reverse T3.

Thyroid-Binding Inhibitory Immunoglobulins (TBIIs): TBIIs completely binds to TSH receptors but do not stimulate the thyroid. Instead, they lead to a decrease in the production of thyroid hormones. In rare cases, they have been associated with hyperstimulation, but this is typically in association with TSI.

TSI can be measured on its own. It is a separate and specified analyte. TRAb is typically used to rule out Graves’ disease or autoimmune hyperthyroidism.

TRAb in Pregnancy

It is not uncommon for all thyroid antibodies to increase in the first trimester if present preconception. Levels may then increase or decrease based on individual presentations. With changes in immune-system function and globulin production, in normal pregnancy, antibodies generally decrease slightly in the second and third trimesters.

High TRAb in Pregnancy

​All Graves’ disease patients should be medically managed by endocrinologists. During pregnancy, TRAb crosses the placenta and may induce fetal hyperthyroidism. TRAb levels over three times the upper limit of normal are associated with hyperthyroidism in the fetus and newborn.

Most Common Causes of High TRAb 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 TRAb in Pregnancy

Not considered pathogenic

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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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