Thyroid Peroxidase (TPO) Antibodies

CPT: 86376
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  • Antimicrosomal Antibody
  • Antithyroid Microsomal Antibody

Special Instructions

This test may exhibit interference when sample is collected from a person who is consuming a supplement with a high dose of biotin (also termed as vitamin B7 or B8, vitamin H, or coenzyme R). It is recommended to ask all patients who may be indicated for this test about biotin supplementation. Patients should be cautioned to stop biotin consumption at least 72 hours prior to the collection of a sample.

Expected Turnaround Time

Within 1 day

Specimen Requirements


Serum (preferred) or plasma


1 mL

Minimum Volume

0.7 mL (Note: This volume does not allow for repeat testing.)


Red-top tube, gel-barrier tube, or green-top (lithium heparin) tube. Do not use oxalate, EDTA, or citrate plasma.


If a red-top tube or plasma is used, transfer separated serum or plasma to a plastic transport tube.

Storage Instructions

Room temperature

Stability Requirements



Room temperature

14 days


14 days


14 days

Causes for Rejection

Citrate plasma specimen; improper labeling

Test Details


Differential diagnosis of hypothyroidism and thyroiditis


Should be used in conjunction with antithyroglobulin test, since autoimmune thyroiditis may demonstrate a response to antigens other than thyroid microsomes. To order both antithyroglobulin and antimicrosomal tests, use profile 006684. Other autoimmune disorders such as Sjögren's syndrome, lupus erythematosus, rheumatoid arthritis, pernicious anemia, and others may be positive for antimicrosomal and antithyroglobulin. Patients with myxedema, granulomatous thyroiditis, nontoxic nodular goiter, and thyroid carcinoma may occasionally produce thyroid antibodies.


Electrochemiluminescence immunoassay (ECLIA)

Reference Interval

See table.1


Range (IU/mL)

0 to 6 d


7 d to 3 m


4 to 11 m


1 to 5 y


6 to 10 y


11 to 19 y


>19 y


Additional Information

Antibodies to thyroid microsomes (thyroid peroxidase) are present in 70% to 90% of patients with chronic thyroiditis. They are also present in smaller percentages of patients of other thyroid diseases. Antibody production may be confined to lymphocytes within the thyroid, and serum may be negative. Small numbers (3%) of people with no evidence of disease may have antibody. This is more frequent in females and increases with age.


1. Reference Intervals for Children and Adults. Elecsys Thyroid Test. Manneheim, Germany: Roche Diagnostics Corporation; 2009.


Order Code Order Code Name Order Loinc Result Code Result Code Name UofM Result LOINC
006676 Thyroid Peroxidase (TPO) Ab 8099-4 006676 Thyroid Peroxidase (TPO) Ab IU/mL 8099-4

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