Anti-Thyroid Peroxidase (anti-TPO)

What are Anti-TPO Antibodies?
Anti-thyroid peroxidase (anti-TPO) antibodies are autoantibodies that target thyroid peroxidase, an enzyme crucial for the synthesis of thyroid hormones. The presence of these antibodies is primarily associated with autoimmune thyroid diseases, particularly Hashimoto’s thyroiditis and Graves’ disease.

Purpose of the Anti-TPO Test

The anti-TPO test is performed to:

• Diagnose Autoimmune Thyroid Disorders: It is particularly useful in diagnosing Hashimoto’s thyroiditis, where the immune system attacks the thyroid gland.
• Monitor Disease Progression: The test can help assess the severity of autoimmune thyroid disease and guide treatment decisions.

When to Conduct the Test

Healthcare providers may recommend an anti-TPO test when patients exhibit symptoms such as:

• Fatigue
• Weight changes
• Sensitivity to cold
• Hair loss
• Swelling in the neck (goiter)

Testing Procedure

• Sample Collection: A blood sample is drawn from a vein in the arm.
• Preparation: No special preparation is typically required before the test.

Interpreting Results

• Normal Range: Normal levels of anti-TPO antibodies are generally considered to be less than 30 IU/mL, although reference ranges may vary by laboratory.
• Positive Result: Elevated anti-TPO levels indicate an autoimmune response against the thyroid, which is commonly seen in Hashimoto’s thyroiditis (80-95% of cases) and Graves’ disease (65-80% of cases).

Clinical Implications

• Autoimmune Thyroid Disease: High levels of anti-TPO antibodies are indicative of autoimmune thyroid conditions and can lead to hypothyroidism if left untreated.
• Risk Assessment: Even individuals without current thyroid dysfunction may have elevated anti-TPO antibodies, which can increase their risk of developing thyroid disorders in the future.

Conclusion

Anti-thyroid peroxidase antibodies play a vital role in diagnosing and managing autoimmune thyroid diseases. Their presence indicates an ongoing autoimmune process that can significantly impact thyroid function and overall health.

References

1. Ada Health. “Thyroid Peroxidase Antibodies (TPO) Range & Symptoms.” Link
2. Koru Hospital. “What is Anti-TPO?” Link
3. Care Hospitals. “Anti Thyroid Peroxidase (TPO) Test: Purpose, Procedures, Test Results.” Link
4. Mayo Clinic. “Thyroid peroxidase antibody test.” Link
5. PMC. “Normal range of anti–thyroid peroxidase antibody (TPO-Ab) and its association with atherosclerosis.” Link