Updated December 16, 2014.
by Mary J. Shomon

June 29, 2001 -- If your doctor has told you that you have tested positive for the presence of "thyroid antibodies," but you have a normal thyroid stimulating hormone (TSH) level, what does that mean? Typically, it means that you have autoimmune thyroid disease, and that your thyroid is in the process of autoimmune dysfunction. The level of dysfunction may not be significant enough to register as an out-of-range TSH level, but the presence of antibodies may in fact generate hyperthyroid or hypothyroid symptoms.

Many doctors will not treat patients who present clinical symptoms of hypothyroidism, test positive for Hashimoto's antibodies, but have a normal TSH level -- known as being "euthyroid" -- or, "in the normal range."

There are, however, some endocrinologists, as well as holistic MDs, osteopaths and other practitioners who believe that the presence of thyroid antibodies alone is enough to warrant treatment with small amounts of thyroid hormone. If you've tested positive for antibodies, and have a TSH in the "normal range," but still don't feel well, you may with to consult with a practitioner who has this philosophy.

The practice of treating patients who have Hashimoto's thyroiditis but normal range TSH levels is supported by a new study, reported on in the March 2001 issue of the journal Thyroid. In this study, German researchers reported that use of levothyroxine treatment for cases of Hashimoto's autoimmune thyroiditis where TSH had not yet elevated ("euthyroid") beyond normal range could reduce the incidence and degree of autoimmune disease progression.

In the study of 21 patients with euthyroid Hashimoto's Thyroiditis (normal range TSH, but elevated antibodies), half of the patients were treated with levothyroxine for a year, the other half were not treated. After 1 year of therapy with levothyroxine, the antibody levels and lymphocytes (evidence of inflammation) decreased significantly only in the group receiving the medication. Among the untreated group, the antibody levels rose or remained the same.

The researchers concluded that preventative treatment of normal TSH range patients with Hashimoto's disease reduced the various markers of autoimmune thyroiditis, and speculated that that such treatment might even be able to stop the progression of Hashimoto's disease, or perhaps even prevent development of the hypothyroidism.

Journal Reference: Thyroid, 2001 Mar;11(3):249-55, "One-year prophylactic treatment of euthyroid Hashimoto's thyroiditis patients with levothyroxine: is there a benefit?"

More information on autoimmune thyroid disease is available in Living Well With Autoimmune Disease.