Graves’ Disease is an autoimmune disorder that leads to overactivity of the thyroid gland – Hyperthyroidism. Hyperthyroidism occurs when the thyroid makes too much thyroid hormone. Graves’ disease is the most common cause of hyperthyroidism and typically causes thyroid symptoms, eye symptoms and skin symptoms. It is caused by an abnormal immune system response that causes the thyroid gland to produce too much thyroid hormones. Graves’ disease is most common in women over age 20 – however, the disorder may occur at any age and may affect men as well.
Too little thyroid hormone from an underactive thyroid gland is called hypothyroidism. In hypothyroidism, the body's metabolism is slowed. Several causes for this condition exist, most of which affect the thyroid gland directly, impairing its ability to make enough hormone. More rarely, there may be a pituitary gland tumor, which blocks the pituitary from producing TSH. Whether the problem is caused by the thyroid or by the pituitary gland, the result is that the thyroid is producing too few hormones, causing many physical and mental processes to become sluggish. The body consumes less oxygen and produces less body heat.
Hypothalamic disorders cause reduced TSH secretion by impairing the production or transport of TRH to the pituitary gland. Hypothyroidism may occur because the pituitary secretes TSH in insufficient quantities, or secretes TSH with an abnormal glycosylation pattern which reduces the biologic activity of TSH 1,2,3 . Treatment with oral TRH restores the biologic activity of TSH, suggesting that deficient hypothalamic TRH release induces both quantitative and qualitative abnormalities of TSH secretion. TSH molecules with reduced biologic activity may retain their immunologic reactivity in TSH immunoassays, explaining the sometimes observed slightly increased values of serum TSH (up to 10 mU/l) in central hypothyroidism 18, 23 .