It will be appropriate to analyse anti TPO to confirm the diagnosis. When TSH level comes back high, TSH analysis should be repeated. If it again comes back high, antibody examination should be ordered with the pre-diagnosis of hypothyroidism. Antibody examination is unnecessary for the patients with normal TSH levels.

Antibody levels should be investigated for those with a serum TSA level above 4 mIU/L. Investigating serum anti TPO and anti-Tg allows chronic autoimmune thyroiditis, in other words Hashimoto, to be diagnosed.  Elevated level of anti-TPO is seen in 90-95% of patients with Hashimoto's disease and in 60-90% of patients with Graves' disease. Anti-TPO antibody is more determinative in the diagnosis and follow-up of thyroiditis diseases. Due to that, it is unnecessary to order anti Tg antibody test.

As a result of lymphocyte infiltration in thyroiditis, the antibodies elevate. The ratio of lymphocyte infiltration to antibody elevation is directly proportional.  The studies have shown that elevated antibodies increase the risk of permanent hypothyroidism in the later stages of the disease.  The risk of permanent hypothyroidism in a patient with Hashimoto's thyroiditis increases by 5% every year.

Thyroid gland lymphoma should be taken in consideration at very high anti TPO levels. Sudden growth in the thyroid gland of a patient, who is known to have Hashimoto, should suggest thyroid lymphoma.