1.What is hypothyroidism?
Hypothyroidism is a systemic hypometabolic syndrome caused by reduced synthesis and secretion of thyroid hormones or insufficient tissue utilization.
2.What types of hypothyroidism are there?
According to the etiology and location of the lesion.
1. Primary hypothyroidism (lesion of the thyroid gland itself): accounts for more than 95% of all hypothyroidism; common causes include autoimmunity, thyroid surgery and hyperthyroidism.
Surgery and radioactive iodine treatment for hyperthyroidism
2, secondary hypothyroidism (hypothalamic and pituitary lesions): reduced TSH or TRH secretion; common causes: external pituitary irradiation, pituitary macroadenoma, cranial adenoma, and hypothyroidism.
Pituitary macroadenoma, craniopharyngioma and postpartum hemorrhage
3. Peripheral hypothyroidism (thyroid hormone resistance syndrome): Rarely caused by defective functioning of thyroid hormones in peripheral tissues.
It is a family genetic disease, etc. The peripheral target tissues have good hormone uptake function, but the receptors in the nucleus are dysfunctional or lacking.
Therefore, the physiological effect on thyroid hormone is weak
4. Thyroid hormone or thyroid hormone insensitivity aspect syndrome: It is a kind of thyroid function syndrome caused by the resistance of thyroid gland to TSH.
Hypothyroidism.
According to the age of onset, there are three general clinical types.
1. Cretinism (cretinism): Hypofunction begins in the fetal or neonatal period and is called cretinism.
2, juvenile mucinous edema (juvenile hypothyroidism): hypofunction begins in children before sexual development is called juvenile hypothyroidism.
3.Adult hypothyroidism: it starts in adults and is called adult hypothyroidism
3. Is subclinical hypothyroidism a form of hypothyroidism?
We call the condition of normal serum thyroid hormones (T4, T3, FT4, FT3) and elevated thyroid stimulating hormone subclinical hypothyroidism. Hypothyroidism is defined as “a systemic disease caused by insufficient synthesis and physiological effects of thyroid hormones”. Subclinical hypothyroidism is not considered hypothyroidism because the thyroid hormones are in the normal range. Its characteristics are as follows.
(1) Subclinical hypothyroidism is due to impaired thyroid hormone synthesis or release, and the decrease in thyroid hormone inevitably inhibits the feedback of thyrotropin, causing elevated thyrotropin, and the elevated thyrotropin stimulates thyroid enlargement, hyperplasia, and increased compensatory thyroid hormone release to restore normal blood thyroid hormone, but this is the normal thyroid hormone maintained at high thyrotropin levels.
(2) Since thyroid hormones are at normal levels. Therefore, clinically, there are no other hypothyroid signs and symptoms other than goiter, which is related to subclinical hypothyroidism thyrotropin levels. We encounter many subclinical thyroid patients clinically complaining of symptoms such as weakness, coldness, swelling, constipation and memory loss, while in fact these symptoms are not specific and have nothing to do with subclinical hypothyroidism. Therefore, when subclinical hypothyroid patients take thyroid hormone preparations, these symptoms cannot be relieved and treated.
(3) Subclinical hypothyroidism generally does not require treatment unless the patient requests treatment for goiter. Thyroid hormone replacement therapy is effective in the treatment of goiter, but the goiter can recur after discontinuation of the medication. Clinical hypothyroidism occurs in 5% of subclinical hypothyroid patients each year. Once clinical hypothyroidism occurs, replacement therapy with thyroid hormone preparations is required. Treatment with thyroid hormone preparations before clinical hypothyroidism occurs does not prevent the occurrence of clinical hypothyroidism.
4. How does hypothyroidism occur?
An important role of the thyroid gland is the production of thyroid hormones. Thyroid hormones include thyroxine (T4) and triiodothyronine (T3), both of which are low molecular iodine-containing amino acids. Thyroid hormones are indispensable for human life activities. If thyroid hormone production is too low due to thyroid disorders, causing a decrease in systemic metabolism, affecting the function of several systems and bringing a series of symptoms, this is called hypothyroidism (hypothyroidism).
5.Who is prone to hypothyroidism?
(1) Those with a personal history and family history of thyroid disease.
(2) Those with a history of goiter and surgical thyroidectomy and radioiodine treatment.
(3) Individuals with a personal and family history of autoimmune diseases, such as systemic lupus erythematosus, rheumatoid arthritis, type 1 diabetes, etc.
(4) Those with previous findings of elevated serum TSH or positive serum thyroid autoantibodies.