TG

This test measures the amount of thyroglobulin in the blood. It is produced by the thyroid gland and serves as the source of thyroid hormones T4 and T3. It is primarily used as a marker for thyroid cancer treatment and recurrence of thyroid cancer. It is produced in all healthy individuals in low amounts; however, its level increases in response to both papillary and follicular thyroid cancers. The thyroid gland secretes thyroid hormones (T3 and T4). They are essential hormones for the growth and development of our body. For the synthesis of these hormones, thyroglobulin protein is needed. The protein is produced by the follicular cells of the thyroid gland and is stored in the thyroid gland. The protein acts as a substrate for the synthesis of thyroid hormones. It gets attached to the inactive T3 and T4 hormones. When the pituitary gland releases TSH or Thyroid Stimulating Hormone, the attached thyroglobulin is removed and the active form of thyroid hormones is released into the blood. The attached thyroglobulin returns back to the thyroid follicle, where it continues the production of thyroid hormones. Tg protein also stores iodine which helps in the synthesis of thyroid hormone. The serum Tg test is used to measure the amount of thyroglobulin in the blood. In a healthy individual, its level is low in the blood, but an increase in the level is indicative of thyroid disorder. The Tg levels are affected by iodine intake, antibodies against Tg (TgAb), cigarette smoking and level of TSH. In most cases, the thyroglobulin test is prescribed after the thyroid surgery or after the removal of the thyroid gland. Though it is not the diagnostic test for thyroid cancer, it can be used to monitor and check its recurrence(particularly papillary or follicular thyroid cancer). The test also serves as a tumor marker for thyroid cancers. The Thyroglobulin tumor marker test is affected by the presence of antibodies against thyroglobulin, anti-thyroglobulin antibodies(TgAb). They attack the protein and can destroy the thyroid gland. They are usually detected in the presence of autoimmune disorders. TgAb can result in a false low level of thyroglobulin. So, doctors generally prescribe a series of Tg tests to monitor the effectiveness of ongoing thyroid cancer treatment rather than a single test. The low or high levels of thyroglobulin protein along with symptoms like pain in the neck, difficulty in breathing and swallowing, hair loss, fatigue, anxiety and hoarseness of the voice may indicate a thyroid problem. Thyroid disorders are endemic to certain parts of India. The deficiency in iodine intake will increase the Tg levels. This deficiency is common in the Himalayan and sub-Himalayan regions. Certain parts of Andhra Pradesh, Karnataka and Gujarat are known to have large numbers of goitre cases. Also, there is a higher susceptibility of a thyroid disorder in females and people suffering from any other autoimmune disorder.