Blood test for thyroid hormones: decoding and delivery rules
Endocrinology pays special attention to thyroid diseases( thyroid gland).This is due to the fact that the thyroid gland affects the entire body through the hormones it produces.Violation of their synthesis leads to the appearance of a number of rather specific symptoms, but to understand what kind of disease led to such an effect, tests for thyroid hormones are needed.Table of contents: What hormones are associated with thyroid function Thyroid-stimulating hormone( thyrotropin, TSH) Total triiodothyronine( T3) Free triiodothyronine( T3cv) Thyroxine total( T4) Free thyroxine( T4cv) Thyroglobulin( TG) Thyroxin-binding globulin Antibodies to thyroglobulin andThyroid Peroxidase Calcitonin
What hormones are associated with thyroid functionRecommended to read:
The thyroid itself produces iodine-containing substances, collectively called "iodineRoniny ". These include:
- triiodothyronine( T3) - the main active form of the hormone;
- thyroxine( T4) is a precursor of triiodothyronine, which in tissues turns into an active form.
Both these hormones exist in free and bound form, therefore, the analysis is conducted in such a way as to reveal the level of both free hormones and their total number.Calcitonin is a hormone that regulates calcium-phosphorus metabolism.Its level is also determined when diagnosing thyroid diseases.The thyroid-stimulating hormone( thyrotropin), produced by the pituitary gland( a small gland located in the cranial cavity), affects thyrotoxic function. Also check the concentration of certain thyroid-related proteins:
- of thyroglobulin, whose level rises with organ tumors;
- of thyroxin-binding globulin, which provides information on the functional state of the thyroid gland;
- antibodies to thyroglobulin;
- antibodies to the steroid peroxidase.
All these tests are designed to give the endocrinologist the full amount of information needed to diagnose and monitor the course of treatment for thyroid disorders.
Thyroid-stimulating hormone( thyrotropin, TSH)
This substance is produced by the pituitary gland and regulates the functioning of the thyroid gland.It is characterized by fluctuations in concentration depending on the time of day: a maximum of 2-4 hours at night, a minimum of 17-18 hours.It also rises during pregnancy and in old age( slightly). How to take For 12 hours before taking blood, exercise, alcohol intake, and smoking are excluded. Standards TTG
|mU / l|
|Newborns||1,1 - 17,0|
|under 2 months||0,6 - 10, 0|
|2 - 14 months||0,4 - 7,0|
|14 months - 5 years||0,4 - 6,0|
|5 - 14 years||0,4- 5,0|
|14 years and older||0,4 - 4,0|
Elevation of TSH level is noted with:
- tumorPituitary gland;
- contact with lead;
- decreased adrenal function;
- decreased thyroid function;
- severe gestosis;
- taking certain medicines( valproic acid, phenytoin, beta-blockers, antipsychotics, antiemetics, furosemide, some antiarrhythmics, etc.).
The level reduction is noted with:
- hyperthyroidism of pregnant women;
- postpartum necrosis of the pituitary gland;
- trauma to the pituitary gland;
- thyrotoxic adenoma;
- Toxic goiter;
- receiving a number of drugs - anabolic, corticosteroid hormones, cytostatics, beta-adrenomimetics, nifedipine, etc., as well as with replacement therapy for hypothyroidism.
Total triiodothyronine( T3)
This is the main hormone of the thyroid gland.Its level is characterized by seasonal fluctuations with a maximum in September-February and a minimum in the summer. How to take One month before the test, you should stop taking thyroid hormones( except when prohibited by your doctor).2-3 days before the study, iodine-containing drugs are discontinued.The day before you should give up physical exertion, stress.Blood is taken on an empty stomach. Increases when:
- some types of myeloma;
- prompt set of body weight;
- nephrotic syndrome;
- Toxic goiter;
- postpartum thyroid dysfunction;
- chronic liver disease;
- taking certain medications.
- lacks protein in the diet;
- adrenal insufficiency;
- recovery after severe illness;
- for the intake of anabolic, cytotoxic, beta-blockers, anti-inflammatory drugs, etc.
Free triiodothyronine( T3sv)
Stimulates oxygen uptake by tissues and heat production, and shifts the direction of metabolism towards catabolism( disintegration). How to take Preparation for analysis is similar to taking blood for total triiodothyronine.Changes in concentration are noted in the same cases in which the level of total triiodothyronine changes. Standards T3 and T3sv
|nmol / l||Ng / dl|
|15 - 20 years||1.23 - 3.23||80 - 210|
|20 - 50 years||1,08 - 3,14||70 - 205|
|Older than 50 years||0,62 - 2.79||40 - 182|
|pmol / l||pg / mL|
|adults||2,6 - 5,7||0,04-0,087|
Thyroxine General( T4)
This hormone increases the rate of basal metabolism, causing the body tissues( except the brain, spleen and testes) to consume oxygenAnd produce heat.The maximum of its concentration is at the time of 8-12 hours in the morning, a minimum - at midnight hours.Also seasonal fluctuations in the level of total thyroxin with a maximum in September and February and a minimum in the summer months were noted. How to take Preparation for analysis is similar to taking blood for total triiodothyronine.In addition, an analysis should be performed prior to the use of X-ray contrast media. The concentration of the hormone increases with:
- HIV infection;
- thyroiditis and toxic goiter;
- taking some medications.
The concentration of total thyroxin falls with a decrease in thyroid function of any origin, as well as when taking a number of medications.
Free thyroxine( T4cv)
How to take The test should be performed before a biopsy or thyroid scan is performed.If the determination of thyroglobulin concentration is necessary to control the treatment, then the study should be performed 6 weeks after surgery or with the withdrawal of preparations containing iodine radioisotopes.Increase in thyroglobulin concentration is noted in the presence of functional thyroid tumors.Its level decreases with thyroiditis, thyroid hyperfunction, benign organ adenoma.
Protein required for binding of thyroxin and transporting it.Increases in hepatitis, acute intermittent porphyria, in some cases hypothyroidism, pregnancy.Decreases in any situations that are stressful for the body( serious illnesses and surgeries, lack of protein in the diet), as well as with nephrotic syndrome, acromegaly, ovarian hypofunction.
Antibodies to thyroglobulin and thyroid peroxidase
Represents protein molecules that destroy thyroglobulin.Appear in the body in the presence of autoimmune processes that attack the thyroid( Hashimoto's thyroiditis, Graves' disease) and with differentiated carcinoma. Standards blood assay hormones shchitovidki
|thyroxine binding globulin|
|ng / ml|
|adults||220 - 510|
|Antibodies to thyroglobulin|
|IU / ml|
|adults||0 - 100|
|Antibodies to thyroid peroxidase|
|IU / ml|
|adults||0 - 30|
In a healthy person, this hormone takes part in the humoral regulation of calcium metabolism and, to a lesser extent, phosphorus.Calcitonin analysis serves as a highly specific test for the detection of a malignant thyroid tumor - K-cell carcinoma. How to take Blood is taken on an empty stomach.One month before the study, it is necessary to stop taking oral contraceptives.On the eve of exclusion of physical activity and alcohol.It is forbidden to smoke 3 hours before taking blood.Analyzes for thyroid hormones are a fundamental method of diagnosing her pathology.Apply them and to control the effectiveness of treatment.It should be noted that most of these analyzes are based on reference( relative) values.For an accurate diagnosis, the doctor must take into account not only the numbers obtained in the laboratory, but also the clinical picture of the disease and the peculiarities of its course. Bozbey Gennady Andreevich, ambulance doctor