Essentially, the diagnosis of Hashimoto's disease is based on finding thyroid antibodies in the blood. The level of these often increases as the disease progresses. In the late stages when all the thyroid gland has been destroyed, the level of the auto-antibodies may fall to low or undetectable levels.
There is no safe and reliable way of modifying the faulty immunological system that mistakenly believes that your thyroid cells are "foreign." Thus, the basic cause of Hashimoto's thyroiditis is not treated. If the patient had a temporary phase of Hashitoxicosis (Hashimoto's + toxic + condition), a beta-blocker and/or antithyroid medication, such as carbimazole, may be given for a short time. If the gland becomes uncomfortably painful, a short course of corticosteroids may be used in subacute viral thyroiditis. In general, the treatment is the management of the consequences of thyroid failure, although a goiter is sometimes prevented from becoming larger or is reduced in size by giving thyroxine. The essential step is the prevention of hypothyroidism when this is imminent or the correction of hypothyroidism when this has developed. The best treatment is replacement therapy with thyroxine. Occasionally, surgery is required, particularly if there is any possibility that the goiter is due to cancer and not to Hashimoto's disease. This difficulty may arise when the thyroid feels very hard or is enlarged unevenly, but usually a needle biopsy will resolve this diagnostic difficulty.