Hashimoto's thyroiditis is an autoimmune process that is thought to be initiated by the activation of CD4+T (helper) lymphocytes with specificity for thyroid antigens. Hypothyroidism is due to cytotoxic cells and autoantibodies.
Primary treatment is Thyroxine and surgery is only indicated for cosmetic reasons .
Hashimoto's thyroiditis more common in women (male: female ratio 1:10 to 20) between the ages of 30 and 50 years.
Commonly presents as moderately enlarged firm gland discovered on routine physical examination or the awareness of a painless anterior neck mass, although 20% of patients present with hypothyroidism, and 5% present with hyperthyroidism (hashitoxicosis) Chances of lymphoma are more in cases with hashimoto's thyroiditis.
Antibodies include antithyroglobulin (anti-Tg), antimicrosomal or antithyroid peroxidase (anti-TPO) and thyroid-stimulating immunoglobulin (TSI). Anti-Tg and anti-TPO antibody levels they indicate the underlying disorder, usually an autoimmune thyroiditis. Approximately 80% of patients with Hashimoto's thyroiditis have elevated thyroid antibody levels, but levels may also be increased in patients with Graves' disease, multinodular goiter, and, occasionally, with thyroid neoplasms
In Grave's disease antibodies are directed against (TRAbs) (thyroid hormone receptors) (TSI)
The average daily iodine requirement is 0.1 mg. Iodine is rapidly converted to iodide in stomach and jejunum. Iodide is actively transported into the thyroid follicles.
Thyroid Hormone Synthesis involves four steps
1.Thyroid trapping of iodide
2. Oxidation of iodide into iodine and coupling with tyrosine to form monoiodotyrosine and diiodotyrosine.
3. Coupling to form T3 and T4
4.Hydrolisation of Thyroglobulin to release T3 and T4
In the euthyroid state, T4 is produced and released entirely by the thyroid gland, whereas only 20% of the total T3 is produced by the thyroid. Most of the T3 is produced by peripheral deiodination of T4 in the liver, muscles, kidney, and anterior pituitary,
The thyroid gland is capable of autoregulation, which allows it to modify its function independent of TSH. As an adaptation to low iodide intake, the gland preferentially synthesizes T3 rather than T4, thereby increasing the efficiency of secreted hormone. In situations of iodine excess, iodide transport, peroxide generation, synthesis, and secretion of thyroid hormones are inhibited.
Thyroid storm, a manifestation of severe thyrotoxicosis, is avoided by prophylactic treatment with propylthiouracil or methimazole prior to surgery.
Although some or all of these tests may be required at some stage, the initial investigation would be thyroid function tests to look at whether the patient is hypothyroid or hyperthyroid.
Low TSH means hyperthyroidism and is further evaluated with Radio isotope scan. It also suggests lower chance of malignancy
High TSH suggests hypothyroidism most likely Hashimoto's thyroidits