Hypothyroidism - Information Overview

Insufficient levels of thyroid hormones in organs and tissues lead to the development of such a pathological condition as hypothyroidism, a disease first described by V. Gall in 1873. The term "myxedema", coined by V. M. Ord (1878), means only mucous edema of the skin and subcutaneous tissue. It is traditionally used to characterize the most severe forms of hypothyroidism, accompanied by a kind of universal mucous edema.

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Cause and pathogenesis of hypothyroidism

In the vast majority of cases (90-95%) the disease is caused by a pathological process in the thyroid gland itself, which reduces the level of hormone production (primary hypothyroidism). Disruption of the regulatory and stimulating effect of pituitary thyrotropin or hypothalamic releasing factor (thyroliberin) leads to secondary hypothyroidism, which is significantly less common than primary hypothyroidism. The issue of peripheral hypothyroidism, which occurs either due to disruption of thyroid hormone metabolism in the periphery, in particular the formation of inactive, reverse T3 from _T4, or as a result of decreased sensitivity of nuclear receptors of organs and tissues to thyroid hormones, _{has not been resolved in manyways.}

Causes and pathogenesis of hypothyroidism

Symptoms of Hypothyroidism

Primary hypothyroidism, represented mainly by its "idiopathic" form, is more often observed in women aged 40-60. In recent decades, there has been an increase in all autoimmune diseases, including hypothyroidism. In this regard, the age range has significantly expanded (the disease is observed in children, adolescents, and the elderly), and gender has become blurred. Hypothyroidism in elderly patients has acquired special significance in terms of both diagnosis and treatment, in which a number of common non-specific symptoms can be mistakenly attributed to natural age-related involution or organ pathology.

Symptoms of severe hypothyroidism are very polymorphic, and patients present a lot of complaints: lethargy, slowness, rapid fatigue and decreased performance, daytime sleepiness and sleep disturbances at night, memory impairment, dry skin, swelling of the face and limbs, brittle and striated nails, hair loss, weight gain, paresthesia, often heavy or scanty menstruation, sometimes amenorrhea. Many note persistent pain in the lower back, but this symptom disappears as a result of effective thyroid therapy, does not attract the attention of doctors and is usually regarded as a manifestation of osteochondrosis.

Diagnosis and differential diagnosis of hypothyroidism

Diagnosis of severe forms of hypothyroidism, especially in people who have undergone thyroid surgery or received radioactive iodine treatment, which caused autoimmune diseases, does not cause any particular difficulties. It is more difficult to identify mild forms with scanty, not always typical clinical symptoms, especially in elderly patients, where it is easy to suspect cardiovascular insufficiency, kidney disease, etc. In young and middle-aged women, a number of symptoms similar to hypothyroidism are observed in the syndrome of "idiopathic" edema.

The diagnosis of primary hypothyroidism is specified by a number of diagnostic laboratory studies. Functional thyroid insufficiency is characterized by a decrease in the blood level of protein-bound iodine - BBI, butanol-extractable iodine and the degree of absorption ^{of 131} 1 by the thyroid gland, mainly after 24-72 hours (with a norm of 25-50% of the administered dose).

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Treatment of hypothyroidism

The main method of treating all forms of hypothyroidism is replacement therapy with thyroid preparations. TSH preparations have allergenic properties and are not used as a treatment for secondary (pituitary) hypothyroidism. Recently, studies have appeared on the effectiveness of intranasal (400-800-1000 mg) or intravenous (200-400 mg) administration of TRH for 25-30 days in patients with secondary hypothyroidism caused by a defect in endogenous stimulation and secretion of biologically inactive TSH.

The most common domestic drug is thyroidin, obtained from dried thyroid gland of cattle in the form of 0.1 or 0.05 g dragees. The amount and ratio of iodothyronines in thyroidin varies significantly in different batches of the drug. Approximately 0.1 g of thyroidin contains 8-10 mcg T ₃ and 30-40 mcg T ₄. The unstable composition of the drug complicates its use and assessment of its effectiveness, especially in the early stages of treatment, when precise minimum doses are needed. The effectiveness of the drug is reduced, and sometimes completely leveled, also due to its poor absorption by the mucous membrane of the gastrointestinal tract.