Understanding Lab Tests for Hashimoto's Thyroiditis
Written by Private MD Labs Medical Writing Team • Last Updated: September 8, 2025
Hashimoto's thyroiditis is an autoimmune disorder where the body's immune system mistakenly attacks the thyroid gland, leading to chronic inflammation and often resulting in hypothyroidism. Accurate diagnosis requires specific blood tests that can detect the autoimmune response and assess thyroid function.
Top Recommended Test
Thyroid Peroxidase (TPO) and Thyroglobulin Antibodies (TAA)
This comprehensive test measures both TPO and thyroglobulin antibodies, which are the primary markers of Hashimoto's thyroiditis. High levels of these antibodies indicate that the immune system is attacking thyroid proteins, confirming the autoimmune nature of the condition.
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Diagnosing Hashimoto's Thyroiditis
While symptoms like fatigue, weight gain, and cold intolerance may suggest thyroid dysfunction, definitive diagnosis of Hashimoto's thyroiditis relies on blood tests that detect specific antibodies and measure thyroid hormone levels. These tests confirm the autoimmune nature of the condition and distinguish it from other causes of thyroid dysfunction.
Other Relevant Tests
Thyroid Peroxidase (TPO) Antibodies
TPO antibodies are the most common and important marker for Hashimoto's thyroiditis. Elevated levels indicate that the immune system is targeting thyroid peroxidase, an enzyme essential for thyroid hormone production, confirming the autoimmune attack on the thyroid gland.
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Thyroglobulin Antibody (TAA)
This test detects antibodies against thyroglobulin, a protein produced by the thyroid gland. High levels of these antibodies indicate an autoimmune response against the thyroid, supporting the diagnosis of Hashimoto's thyroiditis.
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Tri-iodothyronine (T3) Total
T3 is an active thyroid hormone that is often decreased in Hashimoto's thyroiditis due to the immune system's damage to the thyroid gland. Low T3 levels help assess the functional impact of the autoimmune condition on thyroid hormone production.
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Thyroglobulin, LC/MS/MS
This sensitive test measures thyroglobulin levels in the blood. In Hashimoto's thyroiditis, thyroglobulin levels may be elevated due to inflammation and damage to the thyroid gland, providing additional evidence of thyroid dysfunction.
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Understanding Your Results
Hashimoto's thyroiditis is typically diagnosed when thyroid antibodies (particularly TPO antibodies) are elevated, often accompanied by changes in thyroid hormone levels. Your healthcare provider will interpret these results in conjunction with your symptoms and clinical presentation to develop an appropriate treatment plan.
Important Considerations
The information here is for educational purposes only and is not a substitute for professional medical advice. Always consult with a healthcare provider for diagnosis and treatment.
