Thyroglobulin is a protein precursor of the main thyroid hormones (TG) thyroxine and triiodothyronine. The long protein molecule is able to "break", forming T4 - thyroxine. It, biotransforming, loses an iodine molecule, turning into T3. The resulting hormones play an important role in metabolic processes, so the imbalance of TG leads to impaired thyroid function.
TG description and localization Thyroglobulin is produced in thyroid follicles. Inside the spherical formations there are substances in the form of a colloidal gel. Its main component is TG. The protein is isolated from the rest of the gland space. There is little of it in the blood, and it is released into the bloodstream only when needed. Therefore, an increase in its quantity signals a pathology. Special thyroid cells - thyrocytes extract a protein molecule from the follicles and split it into tyrosine and atomic iodine.
There is a direct correlation between the TG amount in the blood and the thyroid gland size. If hyperproduction of thyroid hormones is noted, then they need more "raw materials". Factors that determine the activity of thyroglobulin are:
· hormone-synthesizing processes activity in the thyroid gland;
· gland volume, presence of nodes and their size;
· inflammatory processes in the thyroid gland.
Also, the TG content in the blood can be increased by:
· violation of the integrity of the follicles, due to physical or chemical trauma, autoimmune processes;
· the use of diagnostic methods requiring the introduction of radioactive iodine into the body;
· purulent fusion of gland tissues;
· postoperative complications after resection, thyroidectomy, and other surgical interventions on the thyroid gland;
· consequences of destruction of gland tissues during laser ablation, fine-needle biopsy and other hardware methods of research and treatment of the thyroid gland.
In some cases, exceeding thyroglobulin norm is a signal to check the thyroid gland for the development of a malignant process in it. An analysis for TG level is recommended to be regularly for patients with a partially removed thyroid gland, if the resection was caused by papillary or follicular thyroid cancer.
In this case, TG is a tumor marker, in the absence of the thyroid gland and a previously removed malignant tumor. In the presence of the organ, the analysis does not make sense and is not prescribed by a good endocrinologist. Therefore, it is considered legitimate to measure the TG level in the blood only to exclude the recurrence of malignant pathology in the thyroid gland after its partial resection.
Terms of appointment and preparation for the test
Patients who have been operated on for follicular or papillary thyroid cancer at least 6 months later receive a referral for TG level testing in the blood. The indication for the appointment is the partial or complete removal of the gland and postoperative radiotherapy performed using radioactive iodine.
The thyroglobulin norm varies widely - from 1.5 to 59 ng / ml. Such a large interval is due to the fact that the given norm is indicated for the state before the thyroid gland removal. After resection, the norm should be 0 ng / ml.
At the same time as the TG test, the detection of antibodies to thyroglobulin is prescribed. Detection of antithyroglobulins may indicate an autoimmune process, but antibodies are also found in postmenopausal women.
It is necessary to prepare for the test in the same way as with any blood sampling from a vein:
· do not eat for 8-12 hours before analysis;
· do not smoke for 3 hours before;
· for 3-4 days before stop taking certain medications after consulting a doctor;
· avoid stress and physical activity on the eve of the test.
The TG test price varies in different regions of the country and medical centers carrying out research. It is worth remembering that this analysis is highly specific and is carried out only for exceptional prescriptions.
Reviews