The work of the endocrine system is almost invisible to humans, but is vital for the functioning of the whole organism. To evaluate its activity, it is necessary to carefully examine thyroid hormones - the norm of these indicators is usually indicated in the sheet with the results of the analyzes. But the correct interpretation presupposes knowledge of certain subtleties of the production of biologically active substances, their purpose.
Norm and pathology in assays for enzymes and thyroid hormones
Before the examination it is important to understand that the thyroid gland itself produces only 2 hormones:
- T3 - triiodothyronine (the main hormone);
- T4 is tetraiodothyronine or thyroxine.
They are necessary for the management of energy metabolism in the body, as well as controlling the activity of such processes as:
- contraction of the heart;
- transmission of impulses along nerve fibers;
- peristalsis of the intestine;
- evaporation of moisture from the surface of the skin and others.
TSH (thyreotropic hormone) is actually produced in the pituitary (brain region), and not in the thyroid gland. It is included in this study, because TSH is necessary to maintain the concentration of T3 and T4 - when their level decreases, the pituitary gland produces thyroid-stimulating hormone more actively.
When determining the amount of triiodothyronine and thyroxin, free values of T3 and T4 are of greater importance, namely they produce the required biological effects.
It is important that not only the thyroid hormone levels are normal, but also the immune response to its enzymes, proteins and tissues. This shows the concentration of antibodies (AT) to the following substances:
- TPO (thyroperoxidase) is the main enzyme of the thyroid gland;
- TG (thyroglobulin) - iodine-containing protein, precursor of T3 and T4;
- thyrotropin hormone receptors.
In addition, the described study defines:
- calcitonin - oncomarker;
- TSH (thyroxine-binding globulin) is a transport protein.
Due to the analysis of the concentration of the above biologically active components, several pathologies can be identified:
- hypo- and hyperplasia of the endocrine organ;
- thyrotoxicosis ;
- autoimmune thyroiditis;
- hypothyroidism ;
- malignant tumor.
What is the norm for thyroid hormones?
For confidence in the results of the study, it is desirable to donate blood in modern laboratories with highly sensitive equipment.
Consider the established boundaries for each indicator.
The norms of the main thyroid hormone Th3 (nmol / L):
- total - 1.06-3.14;
- free - 2.62-5.77.
A strong decrease in T3 indicates hypothyroidism, exhaustion of the endocrine organ, can signal cancer.
The norm of hormones of the pituitary and thyroid gland TTG and T4 is calculated in different units - MED / L and nmol / L, respectively.
Acceptable values for TSH are in the range from 0.47 to 4.15 honey / l.
Common boundaries of T4:
- total - 71.23-142.25;
- free - 9,56-22,3.
Also, when deciphering the results of a test for the content of thyroid hormones in the blood, it is important to know the norms of AT for TPO, TG, and thyrotropic hormone receptors:
- antibodies to thyreperoxidase - less than 5.67 U / ml;
- antibodies to thyroglobulin - titer
- antibodies to pTTG - less than 4 U / l.
The correct values for thyroxin-binding globulin are from 222 to 517 nmol / l.
With regard to the determination of the concentration of calcitonin as an oncomarker in medullary (C-cellular) thyroid cancer, it is performed in specialized institutions. The most reliable is the stimulated analysis, in which blood is taken after intravenous administration of calcium gluconate solution (10%). The slightest increase in calcitonin, even by 0.5 units more than the upper limit of the norm, may indicate a progression of the malignant tumor.