Thyroxine (Thyroxinum) is a diiodotyrosine para-oxyiodophenyl ester. Needle crystals without taste and smell. Contains 65% of iodine. Optically active compound: i-thyroxine acts, three times stronger than d-thyroxine. The strongest catalyst, accelerating the processes of metabolism. For normal life, 15 mg of thyroxine in the human body is sufficient.
Thyroxine and another thyroid hormone triiodothyronine (see) are powerful regulators of metabolic processes in the body. The greatest effect of thyroxin on protein metabolism. With thyroidectomy, the release of nitrogen in the urine is reduced by 50%. With thyrotoxicosis, even with a protein-free diet, the nitrogen content in the urine is increased.
Thyroxine also increases carbohydrate and fat metabolism. The administration of thyroxin causes a marked decrease in glycogen content in the liver, but without the appearance of glycosuria, which is explained by the increased disintegration of carbohydrates. With thyroid hypothyroidism, adrenaline administration causes weaker glycosuria and hyperglycemia. The fat deposits and the cholesterol content in the blood with thyrotoxicosis decrease.
The mechanism of action of thyroxine has not been sufficiently studied. The secretion of thyroxin is affected by the thyroid-stimulating hormone of the anterior lobe of the pituitary gland. Thyroxin, penetrating into the cells of the body, interacts with the enzyme systems of the cell, in particular those associated with the hydrolysis of nutrients and their oxidation.
The synthesized secretion of thyroid follicles associated with protein thyroglobulin is deposited outside the cells in the cavity of the follicles. In this regard, the release of the colloid into the bloodstream can be achieved by its dilution and reverse reabsorption by the cells of the follicular walls. The thyroid-stimulating hormone stimulates the processes of removing the accumulated colloid from the follicles, acting on the secretion secretion phase. Gradually the concentration of thyroxin, resorbed by them from the colloid, increases in the cells, inhibits the effect of the thyroid-stimulating hormone and the metabolic processes in the thyroid cells decrease.
The normal function of the thyroid gland is associated with the intake of the necessary amount of iodide salts in the body, which are the raw materials for the formation of thyroxin and triiodothyronine. With a deficiency of iodine, compensatory hyperplasia and hypertrophy of the thyroid gland with a low content of iodine in it develop. With a lack of iodine, iron at the beginning is still able to perform its function through a more intense activity.
There is a pharmaceutical drug thyroxine, which contains a synthetic thyroid hormone. 1 cm 3 of the drug contains 1.1% synthetic hormone.
Indications and contraindications see Thyreoidin.
Form of issue. Ampoules of 1 cm 3 containing 1 mg of the drug.
Dosage. 0.001-0.002 in the muscles 2-6 times a day.