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Thyroid Peroxidase Antibody (Thyroid Antibody Screen, TPO Antibody)

Published: August 9, 2026Updated: August 16, 2026

This test checks for antibodies against thyroid peroxidase, an enzyme involved in thyroid hormone production. These antibodies may indicate an autoimmune condition affecting the thyroid.

Quick summary

["This test helps identify potential thyroid-related autoimmune disorders that may require further evaluation or treatment."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
87156-6
Short code
Guided Thyroid PC Bx CN
Synonyms
Guided Thyroid PC Bx CN
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
imaging-modality
Specimen volume
5 mL
Stability
Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–24 hours
Order
routine

Why This Test Might Be Ordered

Your healthcare provider may recommend this test if you have symptoms like fatigue, weight changes, or unexplained thyroid issues, or if you have a family history of autoimmune thyroid diseases. It may also be part of routine screening for conditions like Hashimoto’s thyroiditis or Graves’ disease.

What to Expect During the Test

A blood sample will be drawn from a vein in your arm. You may feel a slight pinch, but it usually takes only a few minutes. No special preparation is needed, though fasting may be advised depending on your provider’s instructions.

What the Results Mean

High levels of TPO antibodies suggest an autoimmune reaction targeting your thyroid. Low or normal levels do not indicate a problem, but further testing may still be needed to assess thyroid function (e.g., thyroid-stimulating hormone, or TSH).

Common Symptoms to Watch For

Autoimmune thyroid conditions linked to TPO antibodies may cause symptoms like unexplained weight changes, fatigue, hair loss, or frequent illnesses. If you experience these or other concerning symptoms, discuss them with your provider.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

TPO Antibody

Frequently asked questions

Could I have Hashimoto’s or Graves’ disease based on these results?
While high TPO antibodies strongly suggest an autoimmune thyroid condition, they alone do not diagnose Hashimoto’s or Graves’ disease. Your provider will likely order additional tests, such as TSH levels, to confirm thyroid function and diagnose the specific condition.
What if my TPO antibody levels are normal but I still feel unwell?
Normal TPO antibody results mean no evidence of this specific antibody is detected, but other autoimmune or thyroid-related factors could still be causing your symptoms. Your provider may recommend further testing, including thyroid function tests or other blood markers.
Do I need to take any special steps if my TPO antibody test is positive?
If your TPO antibody test is positive, your healthcare provider may recommend monitoring thyroid function, adjusting medications (if applicable), or referring you to an endocrinologist. Follow their guidance closely to manage your condition effectively.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy