Thyroid
Thyroid peroxidase antibodiesTPO-Ab
Marker of autoimmune thyroiditis (Hashimoto's, Graves').
Sample
Serum
Clinical reference range
— to 35 IU/mL
Negative
Conv: —–35 IU/mL
Biology
What it measures
Antibodies to TPO, the enzyme that iodinates tyrosine on thyroglobulin.
Clinical use
Why we order it
Confirm autoimmune etiology; predict progression of subclinical to overt hypothyroidism (~5%/yr if positive).
Lens · Clinical
Interpretation by lens
Clinical interpretation
Positive in 90% of Hashimoto's, 75% of Graves'; can be present in 10% of healthy women without dysfunction.
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