Anti-TPO & Anti-Thyroglobulin (Thyroid Autoantibodies)
Also known as: Thyroid Peroxidase Antibodies, Thyroid Microsomal Antibodies, Anti-Tg Antibodies, Hashimoto’s Autoantibody Test
Parameters Measured in the Report
A breakdown of individual biomarkers and biological reference intervals typically found in your report:
| Biomarker | Standard Range | Unit | What It Means |
|---|---|---|---|
Anti-Thyroid Peroxidase (Anti-TPO) (TPO Antibodies) | Normal: < 34.0 (or < 9.0 IU/mL depending on specific assay) | IU/mL | Autoantibody attacking the thyroid hormone synthesis enzyme; primary diagnostic marker for Hashimoto’s thyroiditis. |
Anti-Thyroglobulin (Anti-Tg) (Tg Antibodies) | Normal: < 115.0 | IU/mL | Autoantibody attacking stored thyroid matrix protein; evaluated alongside Anti-TPO and during thyroid cancer follow-up. |
* Note: Reference ranges may vary slightly between testing instruments and reagent kits. Always refer to the reference interval printed on your specific pathology report.
Clinical Focus
Autoantibodies directed against thyroid peroxidase (TPO) enzyme and thyroglobulin (Tg) matrix protein in thyroid follicles.
Sample & Specimen
Venous blood (Serum tube)
Fasting Protocol
No fasting required. Maintain regular diet and fluid intake.
Turnaround Time
12–24 hours
What Is This Test?
Why Did Your Doctor Order This Test?
Physicians routinely prescribe the Anti-TPO & Anti-Tg in the following clinical scenarios:
How to Prepare Before Your Test
- No fasting or special preparation required.
- Stop taking high-dose Biotin (Vitamin B7) hair/skin supplements for 48–72 hours prior, as biotin interferes with laboratory immunoassay reagents.
Understanding Your Results
What higher or lower readings generally mean in clinical practice:
If Values Are Higher Than Normal
Significantly elevated Anti-TPO (>100–1,000+ IU/mL) confirms Autoimmune Thyroiditis (Hashimoto’s). In individuals with Subclinical Hypothyroidism (slightly elevated TSH but normal FT4), positive Anti-TPO predicts a 4% to 5% annual progression rate to overt permanent hypothyroidism.
If Values Are Lower Than Normal
Negative or normal Anti-TPO (<34 IU/mL) indicates that an abnormal TSH is likely due to non-autoimmune causes (such as iodine deficiency, medications, surgical removal, or recovery from subacute thyroiditis).
Frequently Asked Questions
If my Anti-TPO is high but my TSH and T4 are normal, do I need thyroid medicine?
Generally, no. High Anti-TPO with normal TSH means your immune system is targeting the thyroid, but your thyroid is still producing adequate hormones. Doctors monitor your TSH annually rather than starting levothyroxine immediately.
Why are thyroid antibodies checked in women with unexplained recurrent miscarriages?
High maternal Anti-TPO antibodies are associated with a doubled risk of first-trimester miscarriage and preterm delivery. Identifying positive antibodies allows endocrinologists to keep TSH tightly managed (<2.5 mIU/L) before conception.
Related Laboratory Tests
Tests frequently prescribed together or used as follow-up investigations:
Thyroid Profile (TFT: TSH, Free T3, Free T4)
Thyroid Stimulating Hormone (TSH), Free Thyroxine (FT4), and Free Triiodothyronine (FT3).
Complete Blood Count (CBC / Hemogram)
Counts and evaluates red blood cells, white blood cells, hemoglobin, hematocrit, and platelets.
Vitamin D3 (25-Hydroxy Vitamin D)
Total circulating concentration of 25-hydroxyvitamin D (D2 and D3 combined).
Lipid Profile (Cholesterol Panel)
Total Cholesterol, HDL (good cholesterol), LDL (bad cholesterol), VLDL, and Triglycerides.
Medical & Diagnostic Disclaimer
This guide is published for educational and patient informational purposes only. It is not a substitute for professional medical evaluation, diagnosis, or clinical advice.
A laboratory result that falls slightly outside standard statistical reference intervals does not automatically indicate disease; conversely, a normal result does not guarantee the absence of medical conditions. Only your attending physician can interpret lab findings in the context of your medical history, physical exam, and symptoms.