This term is used to describe insufficient production or secretion of thyroid hormones. Thyroid dysfunction affects about 7% of the adult population, the incidence increases with age. Statistically, it is about 5 times more common in women than in men. The thyroid gland is an endocrine (endocrine) gland that produces hormones that regulate the metabolic processes of the entire body. Euthyroidism depends on the hypothalamic-pituitary system.
The proper, metabolically active hormone is triiodothyronine, which increases energy metabolism, increases oxygen consumption and heat generation in the body, and in the liver it increases glycogenolysis and gluconeogenesis. It also causes an increase in LDL receptors in the hepatocyte membrane.
The most common symptoms were: weight gain, drowsiness, difficulty concentrating and slowing thinking, feeling cold, freezing easily; dry, cold, pale skin with a yellowish color, reduced sweating, excessive keratosis of the epidermis, e.g. on the elbows, dry, brittle and thinning hair. The full clinical picture of hypothyroidism occurs in adults as a result of the so-called characteristic mucoid edema resulting from the deposition of glycosaminoglycans in the subcutaneous tissue.
The drug of first choice in the treatment of hypothyroidism is levothyroxine (L-T4 [Eltroxin, Euthyrox N, Letrox]) used as monotherapy. The goal of pharmacotherapy is to gradually achieve euthyroidism and the desired serum TSH concentration. The size of the dose depends on many factors: age, lean body mass, pregnancy, etiology, severity, comorbidities, in particular heart diseases.
Dosage is selected individually under the control of plasma TSH concentration. Typically, the daily requirement for LT4 is: 1.6-1.8 µg / kg b.w. Higher doses are used in the case of infection with Helicobacter pylori, atrophic gastritis, and celiac disease. Treatment with levothyroxine is started with a full or partial dose until the target TSH level is reached. The exception is comorbidities such as coronary artery disease. In this case, treatment begins with lower doses, ie 12.5–25 µg / d, due to the risk of drug accumulation. However, in pregnant women, the need for thyroid hormones increases by 40%.
Absorption and metabolism
The condition for proper absorption of LT4 preparation is the maintenance of adequate acidity of gastric juice, which may be changed by food consumption or taking other medications.
There has been a significant reduction in LT4 absorption shortly before or during a meal. Therefore, according to the recommendations, to ensure optimal and uniform absorption, you should take the drug:
60 minutes before breakfast or
3 hours after the last meal
Care should be taken to separate (whenever possible) other drugs or supplements that may interfere with absorption, such as calcium carbonate.
To sum up, after the diagnosis of hypothyroidism, the endocrinologist individually determines the appropriate dosing schedule for each patient on the basis of many guidelines, based on which he will try to normalize the concentration of thyroid hormones.
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